- 23 4月, 2017 5 次提交
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由 Nicholas Piggin 提交于
In preparation for adding more bits to the core idle state word, move the lock bit up, and unlock by flipping the lock bit rather than masking off all but the thread bits. Add branch hints for atomic operations while we're here. Reviewed-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NNicholas Piggin <npiggin@gmail.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Nicholas Piggin 提交于
The ISA specifies power save wakeup due to a machine check exception can cause a machine check interrupt (rather than the usual system reset interrupt). The machine check handler copes with this by doing low level machine check recovery without restoring full state from idle, then queues up a machine check event for logging, then directly executes the same idle instruction it woke from. This minimises the work done before recovery is performed. The problem is that it requires machine specific instructions and knowledge of the book3s idle code. Currently it only has code to handle POWER8 idle, so POWER9 crashes when trying to execute the P8 idle instructions which don't exist in ISAv3.0B. cpu 0x0: Vector: e40 (Emulation Assist) at [c0000000008f3810] pc: c000000000008380: machine_check_handle_early+0x130/0x2f0 lr: c00000000053a098: stop_loop+0x68/0xd0 sp: c0000000008f3a90 msr: 9000000000081001 current = 0xc0000000008a1080 paca = 0xc00000000ffd0000 softe: 0 irq_happened: 0x01 pid = 0, comm = swapper/0 Instead of going to sleep after recovery, do the usual idle wakeup and state restoration by calling into the normal idle wakeup path. This reuses the normal idle wakeup paths. Reviewed-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Reviewed-by: NMahesh J Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: NNicholas Piggin <npiggin@gmail.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Nicholas Piggin 提交于
This reduces the number of nops for POWER8. Reviewed-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NNicholas Piggin <npiggin@gmail.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Nicholas Piggin 提交于
The POWER8 idle code has a neat trick of programming the power on engine to restore a low bit into HSPRG0, so idle wakeup code can test and see if it has been programmed this way and therefore lost all state. Restore time can be reduced if winkle has not been reached. However this messes with our r13 PACA pointer, and requires HSPRG0 to be written to. It also optimizes the slowest and most uncommon case at the expense of another SPR write in the common nap state wakeup. Remove this complexity and assume winkle sleeps always require a state restore. This speedup could be made entirely contained within the winkle idle code by counting per-core winkles and setting a thread bitmap when all have gone to winkle. Reviewed-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NNicholas Piggin <npiggin@gmail.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Nicholas Piggin 提交于
No functional change. Reviewed-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NNicholas Piggin <npiggin@gmail.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 11 4月, 2017 1 次提交
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由 Gautham R. Shenoy 提交于
POWER9 DD1.0 hardware has a bug where the SPRs of a thread waking up from stop 0,1,2 with ESL=1 can endup being misplaced in the core. Thus the HSPRG0 of a thread waking up from can contain the paca pointer of its sibling. This patch implements a context recovery framework within threads of a core, by provisioning space in paca_struct for saving every sibling threads's paca pointers. Basically, we should be able to arrive at the right paca pointer from any of the thread's existing paca pointer. At bootup, during powernv idle-init, we save the paca address of every CPU in each one its siblings paca_struct in the slot corresponding to this CPU's index in the core. On wakeup from a stop, the thread will determine its index in the core from the TIR register and recover its PACA pointer by indexing into the correct slot in the provisioned space in the current PACA. Furthermore, ensure that the NVGPRs are restored from the stack on the way out by setting the NAPSTATELOST in paca. [Changelog written with inputs from svaidy@linux.vnet.ibm.com] Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Reviewed-by: NNicholas Piggin <npiggin@gmail.com> [mpe: Call it a bug] Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 03 3月, 2017 1 次提交
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由 Gautham R. Shenoy 提交于
Commit 09206b60 ("powernv: Pass PSSCR value and mask to power9_idle_stop") added additional code in power_enter_stop() to distinguish between stop requests whose PSSCR had ESL=EC=1 from those which did not. When ESL=EC=1, we do a forward-jump to a location labelled by "1", which had the code to handle the ESL=EC=1 case. Unfortunately just a couple of instructions before this label, is the macro IDLE_STATE_ENTER_SEQ() which also has a label "1" in its expansion. As a result, the current code can result in directly executing stop instruction for deep stop requests with PSSCR ESL=EC=1, without saving the hypervisor state. Fix this BUG by labeling the location that handles ESL=EC=1 case with a more descriptive label ".Lhandle_esl_ec_set" (local label suggestion a la .Lxx from Anton Blanchard). While at it, rename the label "2" labelling the location of the code handling entry into deep stop states with ".Lhandle_deep_stop". For a good measure, change the label in IDLE_STATE_ENTER_SEQ() macro to an not-so commonly used value in order to avoid similar mishaps in the future. Fixes: 09206b60 ("powernv: Pass PSSCR value and mask to power9_idle_stop") Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 07 2月, 2017 1 次提交
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由 Benjamin Herrenschmidt 提交于
All entry points already read the MSR so they can easily do the right thing. Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: NPaul Mackerras <paulus@ozlabs.org> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 31 1月, 2017 2 次提交
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由 Gautham R. Shenoy 提交于
The power9_idle_stop method currently takes only the requested stop level as a parameter and picks up the rest of the PSSCR bits from a hand-coded macro. This is not a very flexible design, especially when the firmware has the capability to communicate the psscr value and the mask associated with a particular stop state via device tree. This patch modifies the power9_idle_stop API to take as parameters the PSSCR value and the PSSCR mask corresponding to the stop state that needs to be set. These PSSCR value and mask are respectively obtained by parsing the "ibm,cpu-idle-state-psscr" and "ibm,cpu-idle-state-psscr-mask" fields from the device tree. In addition to this, the patch adds support for handling stop states for which ESL and EC bits in the PSSCR are zero. As per the architecture, a wakeup from these stop states resumes execution from the subsequent instruction as opposed to waking up at the System Vector. The older firmware sets only the Requested Level (RL) field in the psscr and psscr-mask exposed in the device tree. For older firmware where psscr-mask=0xf, this patch will set the default sane values that the set for for remaining PSSCR fields (i.e PSLL, MTL, ESL, EC, and TR). For the new firmware, the patch will validate that the invariants required by the ISA for the psscr values are maintained by the firmware. This skiboot patch that exports fully populated PSSCR values and the mask for all the stop states can be found here: https://lists.ozlabs.org/pipermail/skiboot/2016-September/004869.html [Optimize the number of instructions before entering STOP with ESL=EC=0, validate the PSSCR values provided by the firimware maintains the invariants required as per the ISA suggested by Balbir Singh] Acked-by: NBalbir Singh <bsingharora@gmail.com> Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Gautham R. Shenoy 提交于
Currently all the low-power idle states are expected to wake up at reset vector 0x100. Which is why the macro IDLE_STATE_ENTER_SEQ that puts the CPU to an idle state and never returns. On ISA v3.0, when the ESL and EC bits in the PSSCR are zero, the CPU is expected to wake up at the next instruction of the idle instruction. This patch adds a new macro named IDLE_STATE_ENTER_SEQ_NORET for the no-return variant and reuses the name IDLE_STATE_ENTER_SEQ for a variant that allows resuming operation at the instruction next to the idle-instruction. Acked-by: NBalbir Singh <bsingharora@gmail.com> Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 24 10月, 2016 2 次提交
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由 Paul Mackerras 提交于
This fixes a race condition where one thread that is entering or leaving a power-saving state can inadvertently ignore the lock bit that was set by another thread, and potentially also clear it. The core_idle_lock_held function is called when the lock bit is seen to be set. It polls the lock bit until it is clear, then does a lwarx to load the word containing the lock bit and thread idle bits so it can be updated. However, it is possible that the value loaded with the lwarx has the lock bit set, even though an immediately preceding lwz loaded a value with the lock bit clear. If this happens then we go ahead and update the word despite the lock bit being set, and when called from pnv_enter_arch207_idle_mode, we will subsequently clear the lock bit. No identifiable misbehaviour has been attributed to this race. This fixes it by checking the lock bit in the value loaded by the lwarx. If it is set then we just go back and keep on polling. Fixes: b32aadc1 ("powerpc/powernv: Fix race in updating core_idle_state") Cc: stable@vger.kernel.org # v4.2+ Signed-off-by: NPaul Mackerras <paulus@ozlabs.org> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Paul Mackerras 提交于
Commit 8117ac6a ("powerpc/powernv: Switch off MMU before entering nap/sleep/rvwinkle mode", 2014-12-10) fixed a race condition where one thread entering a KVM guest could switch the MMU context to the guest while another thread was still in host kernel context with the MMU on. That commit moved the point where a thread entering a power-saving mode set its kvm_hstate.hwthread_state field in its PACA to KVM_HWTHREAD_IN_IDLE from a point where the MMU was on to after the MMU had been switched off. That commit also added a comment explaining that we have to switch to real mode before setting hwthread_state to avoid this race. Nevertheless, commit 4eae2c9a ("powerpc/powernv: Make pnv_powersave_common more generic", 2016-07-08) subsequently moved the setting of hwthread_state back to a point where the MMU is on, thus reintroducing the race, despite the comment saying that this should not be done being included in full in the context lines of the patch that did it. This fixes the race again and adds a bigger and shoutier comment explaining the potential race condition. Fixes: 4eae2c9a ("powerpc/powernv: Make pnv_powersave_common more generic") Cc: stable@vger.kernel.org # v4.8+ Signed-off-by: NPaul Mackerras <paulus@ozlabs.org> Reviewed-by: NShreyas B. Prabhu <shreyasbp@gmail.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 12 9月, 2016 1 次提交
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由 Gautham R. Shenoy 提交于
pnv_wakeup_tb_loss() currently expects cr4 to be "eq" if the CPU is waking up from a complete hypervisor state loss. Hence, it currently restores the SPR contents only if cr4 is "eq". However, after commit bcef83a0 ("powerpc/powernv: Add platform support for stop instruction"), on ISA v3.0 CPUs, the function pnv_restore_hyp_resource() sets cr4 to contain the result of the comparison between the state the CPU has woken up from and the first deep stop state before calling pnv_wakeup_tb_loss(). Thus if the CPU woke up from a state that is deeper than the first deep stop state, cr4 will have "gt" set and hence, pnv_wakeup_tb_loss() will fail to restore the SPRs on waking up from such a state. Fix the code in pnv_wakeup_tb_loss() to restore the SPR states when cr4 is "eq" or "gt". Fixes: bcef83a0 ("powerpc/powernv: Add platform support for stop instruction") Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Reviewed-by: NShreyas B. Prabhu <shreyasbp@gmail.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 09 8月, 2016 2 次提交
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由 Mahesh Salgaonkar 提交于
Move IDLE_STATE_ENTER_SEQ macro to cpuidle.h so that MCE handler changes in subsequent patch can use it. No functionality change. Signed-off-by: NMahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Mahesh Salgaonkar 提交于
The function pnv_restore_hyp_resource() loads the TOC into r2 from the invalid PACA pointer before fixing r13 value. This do not affect POWER ISA 3.0 but it does have an impact on POWER ISA 2.07 or less leading CPU to get stuck forever. login: [ 471.830433] Processor 120 is stuck. This can be easily reproducible using following steps: - Turn off SMT $ ppc64_cpu --smt=off - offline/online any online cpu (Thread 0 of any core which is online) $ echo 0 > /sys/devices/system/cpu/cpu<num>/online $ echo 1 > /sys/devices/system/cpu/cpu<num>/online For POWER ISA 2.07 or less, the last bit of HSPRG0 is set indicating that thread is waking up from winkle. Hence, the last bit of HSPRG0(r13) needs to be clear before accessing it as PACA to avoid loading invalid values from invalid PACA pointer. Fix this by loading TOC after r13 register is corrected. Fixes: bcef83a0 ("powerpc/powernv: Add platform support for stop instruction") Signed-off-by: NMahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Acked-by: NVaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 01 8月, 2016 1 次提交
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由 Aneesh Kumar K.V 提交于
MMU feature bits are defined such that we use the lower half to present MMU family features. Remove the strict split of half and also move Radix to a mmu family feature. Radix introduce a new MMU model and strictly speaking it is a new MMU family. This also free up bits which can be used for individual features later. Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 17 7月, 2016 1 次提交
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由 Benjamin Herrenschmidt 提交于
Replace the old generic opal_call_realmode() with proper per-call wrappers similar to the normal ones and convert callers. Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 15 7月, 2016 7 次提交
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由 Shreyas B. Prabhu 提交于
POWER ISA v3 defines a new idle processor core mechanism. In summary, a) new instruction named stop is added. This instruction replaces instructions like nap, sleep, rvwinkle. b) new per thread SPR named Processor Stop Status and Control Register (PSSCR) is added which controls the behavior of stop instruction. PSSCR layout: ---------------------------------------------------------- | PLS | /// | SD | ESL | EC | PSLL | /// | TR | MTL | RL | ---------------------------------------------------------- 0 4 41 42 43 44 48 54 56 60 PSSCR key fields: Bits 0:3 - Power-Saving Level Status. This field indicates the lowest power-saving state the thread entered since stop instruction was last executed. Bit 42 - Enable State Loss 0 - No state is lost irrespective of other fields 1 - Allows state loss Bits 44:47 - Power-Saving Level Limit This limits the power-saving level that can be entered into. Bits 60:63 - Requested Level Used to specify which power-saving level must be entered on executing stop instruction This patch adds support for stop instruction and PSSCR handling. Reviewed-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NShreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Shreyas B. Prabhu 提交于
Create a function for saving SPRs before entering deep idle states. This function can be reused for POWER9 deep idle states. Reviewed-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NShreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Shreyas B. Prabhu 提交于
pnv_powersave_common does common steps needed before entering idle state and eventually changes MSR to MSR_IDLE and does rfid to pnv_enter_arch207_idle_mode. Move the updation of HSTATE_HWTHREAD_STATE to pnv_powersave_common from pnv_enter_arch207_idle_mode and make it more generic by passing the rfid address as a function parameter. Reviewed-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NShreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Shreyas B. Prabhu 提交于
Functions like power7_wakeup_loss, power7_wakeup_noloss, power7_wakeup_tb_loss are used by POWER7 and POWER8 hardware. They can also be used by POWER9. Hence rename these functions hardware agnostic names. Suggested-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NShreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Shreyas B. Prabhu 提交于
idle_power7.S handles idle entry/exit for POWER7, POWER8 and in next patch for POWER9. Rename the file to a non-hardware specific name. Reviewed-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NShreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Shreyas B. Prabhu 提交于
In the current code, when the thread wakes up in reset vector, some of the state restore code and check for whether a thread needs to branch to kvm is duplicated. Reorder the code such that this duplication is avoided. At a higher level this is what the change looks like- Before this patch - power7_wakeup_tb_loss: restore hypervisor state if (thread needed by kvm) goto kvm_start_guest restore nvgprs, cr, pc rfid to process context power7_wakeup_loss: restore nvgprs, cr, pc rfid to process context reset vector: if (waking from deep idle states) goto power7_wakeup_tb_loss else if (thread needed by kvm) goto kvm_start_guest goto power7_wakeup_loss After this patch - power7_wakeup_tb_loss: restore hypervisor state return power7_restore_hyp_resource(): if (waking from deep idle states) goto power7_wakeup_tb_loss return power7_wakeup_loss: restore nvgprs, cr, pc rfid to process context reset vector: power7_restore_hyp_resource() if (thread needed by kvm) goto kvm_start_guest goto power7_wakeup_loss Reviewed-by: NPaul Mackerras <paulus@samba.org> Reviewed-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: NShreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Shreyas B. Prabhu 提交于
Signed-off-by: NShreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 20 6月, 2016 1 次提交
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由 Mahesh Salgaonkar 提交于
When a guest is assigned to a core it converts the host Timebase (TB) into guest TB by adding guest timebase offset before entering into guest. During guest exit it restores the guest TB to host TB. This means under certain conditions (Guest migration) host TB and guest TB can differ. When we get an HMI for TB related issues the opal HMI handler would try fixing errors and restore the correct host TB value. With no guest running, we don't have any issues. But with guest running on the core we run into TB corruption issues. If we get an HMI while in the guest, the current HMI handler invokes opal hmi handler before forcing guest to exit. The guest exit path subtracts the guest TB offset from the current TB value which may have already been restored with host value by opal hmi handler. This leads to incorrect host and guest TB values. With split-core, things become more complex. With split-core, TB also gets split and each subcore gets its own TB register. When a hmi handler fixes a TB error and restores the TB value, it affects all the TB values of sibling subcores on the same core. On TB errors all the thread in the core gets HMI. With existing code, the individual threads call opal hmi handle independently which can easily throw TB out of sync if we have guest running on subcores. Hence we will need to co-ordinate with all the threads before making opal hmi handler call followed by TB resync. This patch introduces a sibling subcore state structure (shared by all threads in the core) in paca which holds information about whether sibling subcores are in Guest mode or host mode. An array in_guest[] of size MAX_SUBCORE_PER_CORE=4 is used to maintain the state of each subcore. The subcore id is used as index into in_guest[] array. Only primary thread entering/exiting the guest is responsible to set/unset its designated array element. On TB error, we get HMI interrupt on every thread on the core. Upon HMI, this patch will now force guest to vacate the core/subcore. Primary thread from each subcore will then turn off its respective bit from the above bitmap during the guest exit path just after the guest->host partition switch is complete. All other threads that have just exited the guest OR were already in host will wait until all other subcores clears their respective bit. Once all the subcores turn off their respective bit, all threads will will make call to opal hmi handler. It is not necessary that opal hmi handler would resync the TB value for every HMI interrupts. It would do so only for the HMI caused due to TB errors. For rest, it would not touch TB value. Hence to make things simpler, primary thread would call TB resync explicitly once for each core immediately after opal hmi handler instead of subtracting guest offset from TB. TB resync call will restore the TB with host value. Thus we can be sure about the TB state. One of the primary threads exiting the guest will take up the responsibility of calling TB resync. It will use one of the top bits (bit 63) from subcore state flags bitmap to make the decision. The first primary thread (among the subcores) that is able to set the bit will have to call the TB resync. Rest all other threads will wait until TB resync is complete. Once TB resync is complete all threads will then proceed. Signed-off-by: NMahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
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- 03 3月, 2016 1 次提交
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由 Aneesh Kumar K.V 提交于
No code changes. Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 01 12月, 2015 1 次提交
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由 Anton Blanchard 提交于
The UP only lazy floating point and vector optimisations were written back when SMP was not common, and neither glibc nor gcc used vector instructions. Now SMP is very common, glibc aggressively uses vector instructions and gcc autovectorises. We want to add new optimisations that apply to both UP and SMP, but in preparation for that remove these UP only optimisations. Signed-off-by: NAnton Blanchard <anton@samba.org> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 07 7月, 2015 1 次提交
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由 Shreyas B. Prabhu 提交于
core_idle_state is maintained for each core. It uses 0-7 bits to track whether a thread in the core has entered fastsleep or winkle. 8th bit is used as a lock bit. The lock bit is set in these 2 scenarios- - The thread is first in subcore to wakeup from sleep/winkle. - If its the last thread in the core about to enter sleep/winkle While the lock bit is set, if any other thread in the core wakes up, it loops until the lock bit is cleared before proceeding in the wakeup path. This helps prevent race conditions w.r.t fastsleep workaround and prevents threads from switching to process context before core/subcore resources are restored. But, in the path to sleep/winkle entry, we currently don't check for lock-bit. This exposes us to following race when running with subcore on- First thread in the subcorea Another thread in the same waking up core entering sleep/winkle lwarx r15,0,r14 ori r15,r15,PNV_CORE_IDLE_LOCK_BIT stwcx. r15,0,r14 [Code to restore subcore state] lwarx r15,0,r14 [clear thread bit] stwcx. r15,0,r14 andi. r15,r15,PNV_CORE_IDLE_THREAD_BITS stw r15,0(r14) Here, after the thread entering sleep clears its thread bit in core_idle_state, the value is overwritten by the thread waking up. In such cases when the core enters fastsleep, code mistakes an idle thread as running. Because of this, the first thread waking up from fastsleep which is supposed to resync timebase skips it. So we can end up having a core with stale timebase value. This patch fixes the above race by looping on the lock bit even while entering the idle states. Signed-off-by: NShreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Fixes: 7b54e9f213f76 'powernv/powerpc: Add winkle support for offline cpus' Cc: stable@vger.kernel.org # 3.19+ Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 01 5月, 2015 1 次提交
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由 Sam Bobroff 提交于
Patches 7cba160a "powernv/cpuidle: Redesign idle states management" and 77b54e9f "powernv/powerpc: Add winkle support for offline cpus" use non-volatile condition registers (cr2, cr3 and cr4) early in the system reset interrupt handler (system_reset_pSeries()) before it has been determined if state loss has occurred. If state loss has not occurred, control returns via the power7_wakeup_noloss() path which does not restore those condition registers, leaving them corrupted. Fix this by restoring the condition registers in the power7_wakeup_noloss() case. This is apparent when running a KVM guest on hardware that does not support winkle or sleep and the guest makes use of secondary threads. In practice this means Power7 machines, though some early unreleased Power8 machines may also be susceptible. The secondary CPUs are taken off line before the guest is started and they call pnv_smp_cpu_kill_self(). This checks support for sleep states (in this case there is no support) and power7_nap() is called. When the CPU is woken, power7_nap() returns and because the CPU is still off line, the main while loop executes again. The sleep states support test is executed again, but because the tested values cannot have changed, the compiler has optimized the test away and instead we rely on the result of the first test, which has been left in cr3 and/or cr4. With the result overwritten, the wrong branch is taken and power7_winkle() is called on a CPU that does not support it, leading to it stalling. Fixes: 7cba160a ("powernv/cpuidle: Redesign idle states management") Fixes: 77b54e9f ("powernv/powerpc: Add winkle support for offline cpus") [mpe: Massage change log a bit more] Signed-off-by: NSam Bobroff <sam.bobroff@au1.ibm.com> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 23 3月, 2015 1 次提交
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由 Paul Mackerras 提交于
The power7_nap(), power7_sleep() and power7_winkle() functions are called from pnv_smp_cpu_kill_self(), which expects them to return the SRR1 value set by the hardware on wakeup, or 0 if no nap/sleep/winkle occurred. However, in the case where an interrupt needs to be replayed, the logic in power7_powersave_common (the common code for power7_nap et al.) doesn't set r3 to 0 in this case. Instead what we get as the return value is the selector for the type of power-saving mode requested (1, 2 or 3). In fact this should not affect the operation of pnv_smp_cpu_kill_self(), but it is better to get this correct, so this adds an instruction to set r3 to 0 in this case. Signed-off-by: NPaul Mackerras <paulus@samba.org> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 15 12月, 2014 3 次提交
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由 Shreyas B. Prabhu 提交于
Winkle is a deep idle state supported in power8 chips. A core enters winkle when all the threads of the core enter winkle. In this state power supply to the entire chiplet i.e core, private L2 and private L3 is turned off. As a result it gives higher powersavings compared to sleep. But entering winkle results in a total hypervisor state loss. Hence the hypervisor context has to be preserved before entering winkle and restored upon wake up. Power-on Reset Engine (PORE) is a dedicated engine which is responsible for powering on the chiplet during wake up. It can be programmed to restore the register contests of a few specific registers. This patch uses PORE to restore register state wherever possible and uses stack to save and restore rest of the necessary registers. With hypervisor state restore things fall under three categories- per-core state, per-subcore state and per-thread state. To manage this, extend the infrastructure introduced for sleep. Mainly we add a paca variable subcore_sibling_mask. Using this and the core_idle_state we can distingush first thread in core and subcore. Signed-off-by: NShreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Shreyas B. Prabhu 提交于
Deep idle states like sleep and winkle are per core idle states. A core enters these states only when all the threads enter either the particular idle state or a deeper one. There are tasks like fastsleep hardware bug workaround and hypervisor core state save which have to be done only by the last thread of the core entering deep idle state and similarly tasks like timebase resync, hypervisor core register restore that have to be done only by the first thread waking up from these state. The current idle state management does not have a way to distinguish the first/last thread of the core waking/entering idle states. Tasks like timebase resync are done for all the threads. This is not only is suboptimal, but can cause functionality issues when subcores and kvm is involved. This patch adds the necessary infrastructure to track idle states of threads in a per-core structure. It uses this info to perform tasks like fastsleep workaround and timebase resync only once per core. Signed-off-by: NShreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Originally-by: NPreeti U. Murthy <preeti@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Cc: linux-pm@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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由 Paul Mackerras 提交于
Currently, when going idle, we set the flag indicating that we are in nap mode (paca->kvm_hstate.hwthread_state) and then execute the nap (or sleep or rvwinkle) instruction, all with the MMU on. This is bad for two reasons: (a) the architecture specifies that those instructions must be executed with the MMU off, and in fact with only the SF, HV, ME and possibly RI bits set, and (b) this introduces a race, because as soon as we set the flag, another thread can switch the MMU to a guest context. If the race is lost, this thread will typically start looping on relocation-on ISIs at 0xc...4400. This fixes it by setting the MSR as required by the architecture before setting the flag or executing the nap/sleep/rvwinkle instruction. Cc: stable@vger.kernel.org [ shreyas@linux.vnet.ibm.com: Edited to handle LE ] Signed-off-by: NPaul Mackerras <paulus@samba.org> Signed-off-by: NShreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 08 12月, 2014 1 次提交
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由 Paul Mackerras 提交于
When a secondary hardware thread has finished running a KVM guest, we currently put that thread into nap mode using a nap instruction in the KVM code. This changes the code so that instead of doing a nap instruction directly, we instead cause the call to power7_nap() that put the thread into nap mode to return. The reason for doing this is to avoid having the KVM code having to know what low-power mode to put the thread into. In the case of a secondary thread used to run a KVM guest, the thread will be offline from the point of view of the host kernel, and the relevant power7_nap() call is the one in pnv_smp_cpu_disable(). In this case we don't want to clear pending IPIs in the offline loop in that function, since that might cause us to miss the wakeup for the next time the thread needs to run a guest. To tell whether or not to clear the interrupt, we use the SRR1 value returned from power7_nap(), and check if it indicates an external interrupt. We arrange that the return from power7_nap() when we have finished running a guest returns 0, so pending interrupts don't get flushed in that case. Note that it is important a secondary thread that has finished executing in the guest, or that didn't have a guest to run, should not return to power7_nap's caller while the kvm_hstate.hwthread_req flag in the PACA is non-zero, because the return from power7_nap will reenable the MMU, and the MMU might still be in guest context. In this situation we spin at low priority in real mode waiting for hwthread_req to become zero. Signed-off-by: NPaul Mackerras <paulus@samba.org> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 25 9月, 2014 1 次提交
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由 Paul Mackerras 提交于
On PowerNV platforms, when a CPU is offline, we put it into nap mode. It's possible that the CPU wakes up from nap mode while it is still offline due to a stray IPI. A misdirected device interrupt could also potentially cause it to wake up. In that circumstance, we need to clear the interrupt so that the CPU can go back to nap mode. In the past the clearing of the interrupt was accomplished by briefly enabling interrupts and allowing the normal interrupt handling code (do_IRQ() etc.) to handle the interrupt. This has the problem that this code calls irq_enter() and irq_exit(), which call functions such as account_system_vtime() which use RCU internally. Use of RCU is not permitted on offline CPUs and will trigger errors if RCU checking is enabled. To avoid calling into any generic code which might use RCU, we adopt a different method of clearing interrupts on offline CPUs. Since we are on the PowerNV platform, we know that the system interrupt controller is a XICS being driven directly (i.e. not via hcalls) by the kernel. Hence this adds a new icp_native_flush_interrupt() function to the native-mode XICS driver and arranges to call that when an offline CPU is woken from nap. This new function reads the interrupt from the XICS. If it is an IPI, it clears the IPI; if it is a device interrupt, it prints a warning and disables the source. Then it does the end-of-interrupt processing for the interrupt. The other thing that briefly enabling interrupts did was to check and clear the irq_happened flag in this CPU's PACA. Therefore, after flushing the interrupt from the XICS, we also clear all bits except the PACA_IRQ_HARD_DIS (interrupts are hard disabled) bit from the irq_happened flag. The PACA_IRQ_HARD_DIS flag is set by power7_nap() and is left set to indicate that interrupts are hard disabled. This means we then have to ignore that flag in power7_nap(), which is reasonable since it doesn't indicate that any interrupt event needs servicing. Signed-off-by: NPaul Mackerras <paulus@samba.org> Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
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- 05 8月, 2014 2 次提交
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由 Mahesh Salgaonkar 提交于
(NOTE: This patch depends on upstream HMI handling patchset at https://lists.ozlabs.org/pipermail/linuxppc-dev/2014-July/119731.html) The current HMI handling on napping cpus does not take care of endianess issue. On LE host kernel when we wake up from nap due to HMI interrupt we would checkstop while jumping into opal call. There is a similar issue in case of fast sleep wakeup where the code invokes opal_resync_tb opal call without handling LE issue. This patch fixes that as well. With this patch applied, HMIs handling on LE host kernel works fine. Signed-off-by: NMahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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由 Mahesh Salgaonkar 提交于
HMIs are thread specific and can come while thread is in sleep/nap mode. Hence with SMT=off mode we can receive HMIs on sleeping threads. For interrupt received in nap mode, cpu wakes up at system reset vector, clears the interrupt and go back to nap mode again. But HMIs are sticky and they keep happening until we clear reason bits from HMER. Hence add a special check for HMI in reset vector (through power7_wakeup_* functions) and invoke opal call to handle HMI. Signed-off-by: NMahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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- 11 7月, 2014 1 次提交
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由 Preeti U Murthy 提交于
Commit 8d6f7c5a: "powerpc/powernv: Make it possible to skip the IRQHAPPENED check in power7_nap()" added code that prevents cpus from checking for pending interrupts just before entering sleep state, which is wrong. These interrupts are delivered during the soft irq disabled state of the cpu. A cpu cannot enter any idle state with pending interrupts because they will never be serviced until the next time the cpu is woken up by some other interrupt. Its only then that the pending interrupts are replayed. This can result in device timeouts or warnings about this cpu being stuck. This patch fixes ths issue by ensuring that cpus check for pending interrupts just before entering any idle state as long as they are not in the path of split core operations. Signed-off-by: NPreeti U Murthy <preeti@linux.vnet.ibm.com> Acked-by: NMichael Ellerman <mpe@ellerman.id.au> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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- 28 5月, 2014 1 次提交
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由 Michael Ellerman 提交于
To support split core we need to be able to force all secondaries into nap, so the core can detect they are idle and do an unsplit. Currently power7_nap() will return without napping if there is an irq pending. We want to ignore the pending irq and nap anyway, we will deal with the interrupt later. Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au> Signed-off-by: NMichael Neuling <mikey@neuling.org> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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- 23 4月, 2014 1 次提交
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由 Anton Blanchard 提交于
binutils is smart enough to know that a branch to a function descriptor is actually a branch to the functions text address. Alan tells me that binutils has been doing this for 9 years. Signed-off-by: NAnton Blanchard <anton@samba.org>
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