- 05 7月, 2018 5 次提交
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由 Paolo Bonzini 提交于
Add the logic for flushing L1D on VMENTER. The flush depends on the static key being enabled and the new l1tf_flush_l1d flag being set. The flags is set: - Always, if the flush module parameter is 'always' - Conditionally at: - Entry to vcpu_run(), i.e. after executing user space - From the sched_in notifier, i.e. when switching to a vCPU thread. - From vmexit handlers which are considered unsafe, i.e. where sensitive data can be brought into L1D: - The emulator, which could be a good target for other speculative execution-based threats, - The MMU, which can bring host page tables in the L1 cache. - External interrupts - Nested operations that require the MMU (see above). That is vmptrld, vmptrst, vmclear,vmwrite,vmread. - When handling invept,invvpid [ tglx: Split out from combo patch and reduced to a single flag ] Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com> Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Paolo Bonzini 提交于
336996-Speculative-Execution-Side-Channel-Mitigations.pdf defines a new MSR (IA32_FLUSH_CMD aka 0x10B) which has similar write-only semantics to other MSRs defined in the document. The semantics of this MSR is to allow "finer granularity invalidation of caching structures than existing mechanisms like WBINVD. It will writeback and invalidate the L1 data cache, including all cachelines brought in by preceding instructions, without invalidating all caches (eg. L2 or LLC). Some processors may also invalidate the first level level instruction cache on a L1D_FLUSH command. The L1 data and instruction caches may be shared across the logical processors of a core." Use it instead of the loop based L1 flush algorithm. A copy of this document is available at https://bugzilla.kernel.org/show_bug.cgi?id=199511 [ tglx: Avoid allocating pages when the MSR is available ] Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com> Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Paolo Bonzini 提交于
To mitigate the L1 Terminal Fault vulnerability it's required to flush L1D on VMENTER to prevent rogue guests from snooping host memory. CPUs will have a new control MSR via a microcode update to flush L1D with a single MSR write, but in the absence of microcode a fallback to a software based flush algorithm is required. Add a software flush loop which is based on code from Intel. [ tglx: Split out from combo patch ] [ bpetkov: Polish the asm code ] Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com> Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Konrad Rzeszutek Wilk 提交于
Add a mitigation mode parameter "vmentry_l1d_flush" for CVE-2018-3620, aka L1 terminal fault. The valid arguments are: - "always" L1D cache flush on every VMENTER. - "cond" Conditional L1D cache flush, explained below - "never" Disable the L1D cache flush mitigation "cond" is trying to avoid L1D cache flushes on VMENTER if the code executed between VMEXIT and VMENTER is considered safe, i.e. is not bringing any interesting information into L1D which might exploited. [ tglx: Split out from a larger patch ] Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Konrad Rzeszutek Wilk 提交于
If the L1TF CPU bug is present we allow the KVM module to be loaded as the major of users that use Linux and KVM have trusted guests and do not want a broken setup. Cloud vendors are the ones that are uncomfortable with CVE 2018-3620 and as such they are the ones that should set nosmt to one. Setting 'nosmt' means that the system administrator also needs to disable SMT (Hyper-threading) in the BIOS, or via the 'nosmt' command line parameter, or via the /sys/devices/system/cpu/smt/control. See commit 05736e4a ("cpu/hotplug: Provide knobs to control SMT"). Other mitigations are to use task affinity, cpu sets, interrupt binding, etc - anything to make sure that _only_ the same guests vCPUs are running on sibling threads. Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 02 7月, 2018 2 次提交
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由 Thomas Gleixner 提交于
Due to the way Machine Check Exceptions work on X86 hyperthreads it's required to boot up _all_ logical cores at least once in order to set the CR4.MCE bit. So instead of ignoring the sibling threads right away, let them boot up once so they can configure themselves. After they came out of the initial boot stage check whether its a "secondary" sibling and cancel the operation which puts the CPU back into offline state. Reported-by: NDave Hansen <dave.hansen@intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Tested-by: NTony Luck <tony.luck@intel.com>
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由 Thomas Gleixner 提交于
Dave Hansen reported, that it's outright dangerous to keep SMT siblings disabled completely so they are stuck in the BIOS and wait for SIPI. The reason is that Machine Check Exceptions are broadcasted to siblings and the soft disabled sibling has CR4.MCE = 0. If a MCE is delivered to a logical core with CR4.MCE = 0, it asserts IERR#, which shuts down or reboots the machine. The MCE chapter in the SDM contains the following blurb: Because the logical processors within a physical package are tightly coupled with respect to shared hardware resources, both logical processors are notified of machine check errors that occur within a given physical processor. If machine-check exceptions are enabled when a fatal error is reported, all the logical processors within a physical package are dispatched to the machine-check exception handler. If machine-check exceptions are disabled, the logical processors enter the shutdown state and assert the IERR# signal. When enabling machine-check exceptions, the MCE flag in control register CR4 should be set for each logical processor. Reverting the commit which ignores siblings at enumeration time solves only half of the problem. The core cpuhotplug logic needs to be adjusted as well. This thoughtful engineered mechanism also turns the boot process on all Intel HT enabled systems into a MCE lottery. MCE is enabled on the boot CPU before the secondary CPUs are brought up. Depending on the number of physical cores the window in which this situation can happen is smaller or larger. On a HSW-EX it's about 750ms: MCE is enabled on the boot CPU: [ 0.244017] mce: CPU supports 22 MCE banks The corresponding sibling #72 boots: [ 1.008005] .... node #0, CPUs: #72 That means if an MCE hits on physical core 0 (logical CPUs 0 and 72) between these two points the machine is going to shutdown. At least it's a known safe state. It's obvious that the early boot can be hit by an MCE as well and then runs into the same situation because MCEs are not yet enabled on the boot CPU. But after enabling them on the boot CPU, it does not make any sense to prevent the kernel from recovering. Adjust the nosmt kernel parameter documentation as well. Reverts: 2207def7 ("x86/apic: Ignore secondary threads if nosmt=force") Reported-by: NDave Hansen <dave.hansen@intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Tested-by: NTony Luck <tony.luck@intel.com>
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- 30 6月, 2018 1 次提交
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由 Michal Hocko 提交于
Jan has noticed that pte_pfn and co. resp. pfn_pte are incorrect for CONFIG_PAE because phys_addr_t is wider than unsigned long and so the pte_val reps. shift left would get truncated. Fix this up by using proper types. Fixes: 6b28baca ("x86/speculation/l1tf: Protect PROT_NONE PTEs against speculation") Reported-by: NJan Beulich <JBeulich@suse.com> Signed-off-by: NMichal Hocko <mhocko@suse.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NVlastimil Babka <vbabka@suse.cz>
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- 27 6月, 2018 1 次提交
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由 Vlastimil Babka 提交于
The PAE 3-level paging code currently doesn't mitigate L1TF by flipping the offset bits, and uses the high PTE word, thus bits 32-36 for type, 37-63 for offset. The lower word is zeroed, thus systems with less than 4GB memory are safe. With 4GB to 128GB the swap type selects the memory locations vulnerable to L1TF; with even more memory, also the swap offfset influences the address. This might be a problem with 32bit PAE guests running on large 64bit hosts. By continuing to keep the whole swap entry in either high or low 32bit word of PTE we would limit the swap size too much. Thus this patch uses the whole PAE PTE with the same layout as the 64bit version does. The macros just become a bit tricky since they assume the arch-dependent swp_entry_t to be 32bit. Signed-off-by: NVlastimil Babka <vbabka@suse.cz> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NMichal Hocko <mhocko@suse.com>
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- 22 6月, 2018 1 次提交
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由 Borislav Petkov 提交于
The TOPOEXT reenablement is a workaround for broken BIOSen which didn't enable the CPUID bit. amd_get_topology_early(), however, relies on that bit being set so that it can read out the CPUID leaf and set smp_num_siblings properly. Move the reenablement up to early_init_amd(). While at it, simplify amd_get_topology_early(). Signed-off-by: NBorislav Petkov <bp@suse.de> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 21 6月, 2018 25 次提交
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由 Konrad Rzeszutek Wilk 提交于
336996-Speculative-Execution-Side-Channel-Mitigations.pdf defines a new MSR (IA32_FLUSH_CMD) which is detected by CPUID.7.EDX[28]=1 bit being set. This new MSR "gives software a way to invalidate structures with finer granularity than other architectual methods like WBINVD." A copy of this document is available at https://bugzilla.kernel.org/show_bug.cgi?id=199511Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Vlastimil Babka 提交于
The previous patch has limited swap file size so that large offsets cannot clear bits above MAX_PA/2 in the pte and interfere with L1TF mitigation. It assumed that offsets are encoded starting with bit 12, same as pfn. But on x86_64, offsets are encoded starting with bit 9. Thus the limit can be raised by 3 bits. That means 16TB with 42bit MAX_PA and 256TB with 46bit MAX_PA. Fixes: 377eeaa8 ("x86/speculation/l1tf: Limit swap file size to MAX_PA/2") Signed-off-by: NVlastimil Babka <vbabka@suse.cz> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Thomas Gleixner 提交于
nosmt on the kernel command line merely prevents the onlining of the secondary SMT siblings. nosmt=force makes the APIC detection code ignore the secondary SMT siblings completely, so they even do not show up as possible CPUs. That reduces the amount of memory allocations for per cpu variables and saves other resources from being allocated too large. This is not fully equivalent to disabling SMT in the BIOS because the low level SMT enabling in the BIOS can result in partitioning of resources between the siblings, which is not undone by just ignoring them. Some CPUs can use the full resources when their sibling is not onlined, but this is depending on the CPU family and model and it's not well documented whether this applies to all partitioned resources. That means depending on the workload disabling SMT in the BIOS might result in better performance. Linus analysis of the Intel manual: The intel optimization manual is not very clear on what the partitioning rules are. I find: "In general, the buffers for staging instructions between major pipe stages are partitioned. These buffers include µop queues after the execution trace cache, the queues after the register rename stage, the reorder buffer which stages instructions for retirement, and the load and store buffers. In the case of load and store buffers, partitioning also provided an easier implementation to maintain memory ordering for each logical processor and detect memory ordering violations" but some of that partitioning may be relaxed if the HT thread is "not active": "In Intel microarchitecture code name Sandy Bridge, the micro-op queue is statically partitioned to provide 28 entries for each logical processor, irrespective of software executing in single thread or multiple threads. If one logical processor is not active in Intel microarchitecture code name Ivy Bridge, then a single thread executing on that processor core can use the 56 entries in the micro-op queue" but I do not know what "not active" means, and how dynamic it is. Some of that partitioning may be entirely static and depend on the early BIOS disabling of HT, and even if we park the cores, the resources will just be wasted. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
To support force disabling of SMT it's required to know the number of thread siblings early. amd_get_topology() cannot be called before the APIC driver is selected, so split out the part which initializes smp_num_siblings and invoke it from amd_early_init(). Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Borislav Petkov 提交于
Old code used to check whether CPUID ext max level is >= 0x80000008 because that last leaf contains the number of cores of the physical CPU. The three functions called there now do not depend on that leaf anymore so the check can go. Signed-off-by: NBorislav Petkov <bp@suse.de> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
Make use of the new early detection function to initialize smp_num_siblings on the boot cpu before the MP-Table or ACPI/MADT scan happens. That's required for force disabling SMT. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
To support force disabling of SMT it's required to know the number of thread siblings early. detect_extended_topology() cannot be called before the APIC driver is selected, so split out the part which initializes smp_num_siblings. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
To support force disabling of SMT it's required to know the number of thread siblings early. detect_ht() cannot be called before the APIC driver is selected, so split out the part which initializes smp_num_siblings. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
Real 32bit AMD CPUs do not have SMT and the only value of the call was to reach the magic printout which got removed. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
The value of this printout is dubious at best and there is no point in having it in two different places along with convoluted ways to reach it. Remove it completely. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
Provide a command line and a sysfs knob to control SMT. The command line options are: 'nosmt': Enumerate secondary threads, but do not online them 'nosmt=force': Ignore secondary threads completely during enumeration via MP table and ACPI/MADT. The sysfs control file has the following states (read/write): 'on': SMT is enabled. Secondary threads can be freely onlined 'off': SMT is disabled. Secondary threads, even if enumerated cannot be onlined 'forceoff': SMT is permanentely disabled. Writes to the control file are rejected. 'notsupported': SMT is not supported by the CPU The command line option 'nosmt' sets the sysfs control to 'off'. This can be changed to 'on' to reenable SMT during runtime. The command line option 'nosmt=force' sets the sysfs control to 'forceoff'. This cannot be changed during runtime. When SMT is 'on' and the control file is changed to 'off' then all online secondary threads are offlined and attempts to online a secondary thread later on are rejected. When SMT is 'off' and the control file is changed to 'on' then secondary threads can be onlined again. The 'off' -> 'on' transition does not automatically online the secondary threads. When the control file is set to 'forceoff', the behaviour is the same as setting it to 'off', but the operation is irreversible and later writes to the control file are rejected. When the control status is 'notsupported' then writes to the control file are rejected. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
Split out the inner workings of do_cpu_down() to allow reuse of that function for the upcoming SMT disabling mechanism. No functional change. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
The asymmetry caused a warning to trigger if the bootup was stopped in state CPUHP_AP_ONLINE_IDLE. The warning no longer triggers as kthread_park() can now be invoked on already or still parked threads. But there is still no reason to have this be asymmetric. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
Provide information whether SMT is supoorted by the CPUs. Preparatory patch for SMT control mechanism. Suggested-by: NDave Hansen <dave.hansen@intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Thomas Gleixner 提交于
If the CPU is supporting SMT then the primary thread can be found by checking the lower APIC ID bits for zero. smp_num_siblings is used to build the mask for the APIC ID bits which need to be taken into account. This uses the MPTABLE or ACPI/MADT supplied APIC ID, which can be different than the initial APIC ID in CPUID. But according to AMD the lower bits have to be consistent. Intel gave a tentative confirmation as well. Preparatory patch to support disabling SMT at boot/runtime. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
The static key sched_smt_present is only updated at boot time when SMT siblings have been detected. Booting with maxcpus=1 and bringing the siblings online after boot rebuilds the scheduling domains correctly but does not update the static key, so the SMT code is not enabled. Let the key be updated in the scheduler CPU hotplug code to fix this. Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: NIngo Molnar <mingo@kernel.org>
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由 Konrad Rzeszutek Wilk 提交于
The pr_warn in l1tf_select_mitigation would have used the prior pr_fmt which was defined as "Spectre V2 : ". Move the function to be past SSBD and also define the pr_fmt. Fixes: 17dbca11 ("x86/speculation/l1tf: Add sysfs reporting for l1tf") Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Andi Kleen 提交于
For the L1TF workaround its necessary to limit the swap file size to below MAX_PA/2, so that the higher bits of the swap offset inverted never point to valid memory. Add a mechanism for the architecture to override the swap file size check in swapfile.c and add a x86 specific max swapfile check function that enforces that limit. The check is only enabled if the CPU is vulnerable to L1TF. In VMs with 42bit MAX_PA the typical limit is 2TB now, on a native system with 46bit PA it is 32TB. The limit is only per individual swap file, so it's always possible to exceed these limits with multiple swap files or partitions. Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com> Acked-by: NMichal Hocko <mhocko@suse.com> Acked-by: NDave Hansen <dave.hansen@intel.com>
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由 Andi Kleen 提交于
For L1TF PROT_NONE mappings are protected by inverting the PFN in the page table entry. This sets the high bits in the CPU's address space, thus making sure to point to not point an unmapped entry to valid cached memory. Some server system BIOSes put the MMIO mappings high up in the physical address space. If such an high mapping was mapped to unprivileged users they could attack low memory by setting such a mapping to PROT_NONE. This could happen through a special device driver which is not access protected. Normal /dev/mem is of course access protected. To avoid this forbid PROT_NONE mappings or mprotect for high MMIO mappings. Valid page mappings are allowed because the system is then unsafe anyways. It's not expected that users commonly use PROT_NONE on MMIO. But to minimize any impact this is only enforced if the mapping actually refers to a high MMIO address (defined as the MAX_PA-1 bit being set), and also skip the check for root. For mmaps this is straight forward and can be handled in vm_insert_pfn and in remap_pfn_range(). For mprotect it's a bit trickier. At the point where the actual PTEs are accessed a lot of state has been changed and it would be difficult to undo on an error. Since this is a uncommon case use a separate early page talk walk pass for MMIO PROT_NONE mappings that checks for this condition early. For non MMIO and non PROT_NONE there are no changes. Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com> Acked-by: NDave Hansen <dave.hansen@intel.com>
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由 Andi Kleen 提交于
L1TF core kernel workarounds are cheap and normally always enabled, However they still should be reported in sysfs if the system is vulnerable or mitigated. Add the necessary CPU feature/bug bits. - Extend the existing checks for Meltdowns to determine if the system is vulnerable. All CPUs which are not vulnerable to Meltdown are also not vulnerable to L1TF - Check for 32bit non PAE and emit a warning as there is no practical way for mitigation due to the limited physical address bits - If the system has more than MAX_PA/2 physical memory the invert page workarounds don't protect the system against the L1TF attack anymore, because an inverted physical address will also point to valid memory. Print a warning in this case and report that the system is vulnerable. Add a function which returns the PFN limit for the L1TF mitigation, which will be used in follow up patches for sanity and range checks. [ tglx: Renamed the CPU feature bit to L1TF_PTEINV ] Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com> Acked-by: NDave Hansen <dave.hansen@intel.com>
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由 Andi Kleen 提交于
The L1TF workaround doesn't make any attempt to mitigate speculate accesses to the first physical page for zeroed PTEs. Normally it only contains some data from the early real mode BIOS. It's not entirely clear that the first page is reserved in all configurations, so add an extra reservation call to make sure it is really reserved. In most configurations (e.g. with the standard reservations) it's likely a nop. Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com> Acked-by: NDave Hansen <dave.hansen@intel.com>
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由 Andi Kleen 提交于
When PTEs are set to PROT_NONE the kernel just clears the Present bit and preserves the PFN, which creates attack surface for L1TF speculation speculation attacks. This is important inside guests, because L1TF speculation bypasses physical page remapping. While the host has its own migitations preventing leaking data from other VMs into the guest, this would still risk leaking the wrong page inside the current guest. This uses the same technique as Linus' swap entry patch: while an entry is is in PROTNONE state invert the complete PFN part part of it. This ensures that the the highest bit will point to non existing memory. The invert is done by pte/pmd_modify and pfn/pmd/pud_pte for PROTNONE and pte/pmd/pud_pfn undo it. This assume that no code path touches the PFN part of a PTE directly without using these primitives. This doesn't handle the case that MMIO is on the top of the CPU physical memory. If such an MMIO region was exposed by an unpriviledged driver for mmap it would be possible to attack some real memory. However this situation is all rather unlikely. For 32bit non PAE the inversion is not done because there are really not enough bits to protect anything. Q: Why does the guest need to be protected when the HyperVisor already has L1TF mitigations? A: Here's an example: Physical pages 1 2 get mapped into a guest as GPA 1 -> PA 2 GPA 2 -> PA 1 through EPT. The L1TF speculation ignores the EPT remapping. Now the guest kernel maps GPA 1 to process A and GPA 2 to process B, and they belong to different users and should be isolated. A sets the GPA 1 PA 2 PTE to PROT_NONE to bypass the EPT remapping and gets read access to the underlying physical page. Which in this case points to PA 2, so it can read process B's data, if it happened to be in L1, so isolation inside the guest is broken. There's nothing the hypervisor can do about this. This mitigation has to be done in the guest itself. [ tglx: Massaged changelog ] Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com> Acked-by: NMichal Hocko <mhocko@suse.com> Acked-by: NVlastimil Babka <vbabka@suse.cz> Acked-by: NDave Hansen <dave.hansen@intel.com>
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由 Linus Torvalds 提交于
With L1 terminal fault the CPU speculates into unmapped PTEs, and resulting side effects allow to read the memory the PTE is pointing too, if its values are still in the L1 cache. For swapped out pages Linux uses unmapped PTEs and stores a swap entry into them. To protect against L1TF it must be ensured that the swap entry is not pointing to valid memory, which requires setting higher bits (between bit 36 and bit 45) that are inside the CPUs physical address space, but outside any real memory. To do this invert the offset to make sure the higher bits are always set, as long as the swap file is not too big. Note there is no workaround for 32bit !PAE, or on systems which have more than MAX_PA/2 worth of memory. The later case is very unlikely to happen on real systems. [AK: updated description and minor tweaks by. Split out from the original patch ] Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Tested-by: NAndi Kleen <ak@linux.intel.com> Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com> Acked-by: NMichal Hocko <mhocko@suse.com> Acked-by: NVlastimil Babka <vbabka@suse.cz> Acked-by: NDave Hansen <dave.hansen@intel.com>
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由 Linus Torvalds 提交于
If pages are swapped out, the swap entry is stored in the corresponding PTE, which has the Present bit cleared. CPUs vulnerable to L1TF speculate on PTE entries which have the present bit set and would treat the swap entry as phsyical address (PFN). To mitigate that the upper bits of the PTE must be set so the PTE points to non existent memory. The swap entry stores the type and the offset of a swapped out page in the PTE. type is stored in bit 9-13 and offset in bit 14-63. The hardware ignores the bits beyond the phsyical address space limit, so to make the mitigation effective its required to start 'offset' at the lowest possible bit so that even large swap offsets do not reach into the physical address space limit bits. Move offset to bit 9-58 and type to bit 59-63 which are the bits that hardware generally doesn't care about. That, in turn, means that if you on desktop chip with only 40 bits of physical addressing, now that the offset starts at bit 9, there needs to be 30 bits of offset actually *in use* until bit 39 ends up being set, which means when inverted it will again point into existing memory. So that's 4 terabyte of swap space (because the offset is counted in pages, so 30 bits of offset is 42 bits of actual coverage). With bigger physical addressing, that obviously grows further, until the limit of the offset is hit (at 50 bits of offset - 62 bits of actual swap file coverage). This is a preparatory change for the actual swap entry inversion to protect against L1TF. [ AK: Updated description and minor tweaks. Split into two parts ] [ tglx: Massaged changelog ] Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Tested-by: NAndi Kleen <ak@linux.intel.com> Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com> Acked-by: NMichal Hocko <mhocko@suse.com> Acked-by: NVlastimil Babka <vbabka@suse.cz> Acked-by: NDave Hansen <dave.hansen@intel.com>
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由 Andi Kleen 提交于
L1 Terminal Fault (L1TF) is a speculation related vulnerability. The CPU speculates on PTE entries which do not have the PRESENT bit set, if the content of the resulting physical address is available in the L1D cache. The OS side mitigation makes sure that a !PRESENT PTE entry points to a physical address outside the actually existing and cachable memory space. This is achieved by inverting the upper bits of the PTE. Due to the address space limitations this only works for 64bit and 32bit PAE kernels, but not for 32bit non PAE. This mitigation applies to both host and guest kernels, but in case of a 64bit host (hypervisor) and a 32bit PAE guest, inverting the upper bits of the PAE address space (44bit) is not enough if the host has more than 43 bits of populated memory address space, because the speculation treats the PTE content as a physical host address bypassing EPT. The host (hypervisor) protects itself against the guest by flushing L1D as needed, but pages inside the guest are not protected against attacks from other processes inside the same guest. For the guest the inverted PTE mask has to match the host to provide the full protection for all pages the host could possibly map into the guest. The hosts populated address space is not known to the guest, so the mask must cover the possible maximal host address space, i.e. 52 bit. On 32bit PAE the maximum PTE mask is currently set to 44 bit because that is the limit imposed by 32bit unsigned long PFNs in the VMs. This limits the mask to be below what the host could possible use for physical pages. The L1TF PROT_NONE protection code uses the PTE masks to determine which bits to invert to make sure the higher bits are set for unmapped entries to prevent L1TF speculation attacks against EPT inside guests. In order to invert all bits that could be used by the host, increase __PHYSICAL_PAGE_SHIFT to 52 to match 64bit. The real limit for a 32bit PAE kernel is still 44 bits because all Linux PTEs are created from unsigned long PFNs, so they cannot be higher than 44 bits on a 32bit kernel. So these extra PFN bits should be never set. The only users of this macro are using it to look at PTEs, so it's safe. [ tglx: Massaged changelog ] Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com> Acked-by: NMichal Hocko <mhocko@suse.com> Acked-by: NDave Hansen <dave.hansen@intel.com>
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- 17 6月, 2018 5 次提交
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由 Linus Torvalds 提交于
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git://git.kernel.dk/linux-block由 Linus Torvalds 提交于
Pull block fixes from Jens Axboe: "A collection of fixes that should go into -rc1. This contains: - bsg_open vs bsg_unregister race fix (Anatoliy) - NVMe pull request from Christoph, with fixes for regressions in this window, FC connect/reconnect path code unification, and a trace point addition. - timeout fix (Christoph) - remove a few unused functions (Christoph) - blk-mq tag_set reinit fix (Roman)" * tag 'for-linus-20180616' of git://git.kernel.dk/linux-block: bsg: fix race of bsg_open and bsg_unregister block: remov blk_queue_invalidate_tags nvme-fabrics: fix and refine state checks in __nvmf_check_ready nvme-fabrics: handle the admin-only case properly in nvmf_check_ready nvme-fabrics: refactor queue ready check blk-mq: remove blk_mq_tagset_iter nvme: remove nvme_reinit_tagset nvme-fc: fix nulling of queue data on reconnect nvme-fc: remove reinit_request routine blk-mq: don't time out requests again that are in the timeout handler nvme-fc: change controllers first connect to use reconnect path nvme: don't rely on the changed namespace list log nvmet: free smart-log buffer after use nvme-rdma: fix error flow during mapping request data nvme: add bio remapping tracepoint nvme: fix NULL pointer dereference in nvme_init_subsystem blk-mq: reinit q->tag_set_list entry only after grace period
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git://linuxtv.org/mchehab/experimental由 Linus Torvalds 提交于
Pull documentation fixes from Mauro Carvalho Chehab: "This solves a series of broken links for files under Documentation, and improves a script meant to detect such broken links (see scripts/documentation-file-ref-check). The changes on this series are: - can.rst: fix a footnote reference; - crypto_engine.rst: Fix two parsing warnings; - Fix a lot of broken references to Documentation/*; - improve the scripts/documentation-file-ref-check script, in order to help detecting/fixing broken references, preventing false-positives. After this patch series, only 33 broken references to doc files are detected by scripts/documentation-file-ref-check" * tag 'docs-broken-links' of git://linuxtv.org/mchehab/experimental: (26 commits) fix a series of Documentation/ broken file name references Documentation: rstFlatTable.py: fix a broken reference ABI: sysfs-devices-system-cpu: remove a broken reference devicetree: fix a series of wrong file references devicetree: fix name of pinctrl-bindings.txt devicetree: fix some bindings file names MAINTAINERS: fix location of DT npcm files MAINTAINERS: fix location of some display DT bindings kernel-parameters.txt: fix pointers to sound parameters bindings: nvmem/zii: Fix location of nvmem.txt docs: Fix more broken references scripts/documentation-file-ref-check: check tools/*/Documentation scripts/documentation-file-ref-check: get rid of false-positives scripts/documentation-file-ref-check: hint: dash or underline scripts/documentation-file-ref-check: add a fix logic for DT scripts/documentation-file-ref-check: accept more wildcards at filenames scripts/documentation-file-ref-check: fix help message media: max2175: fix location of driver's companion documentation media: v4l: fix broken video4linux docs locations media: dvb: point to the location of the old README.dvb-usb file ...
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git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs由 Linus Torvalds 提交于
Pull fsnotify updates from Jan Kara: "fsnotify cleanups unifying handling of different watch types. This is the shortened fsnotify series from Amir with the last five patches pulled out. Amir has modified those patches to not change struct inode but obviously it's too late for those to go into this merge window" * tag 'fsnotify_for_v4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: fsnotify: add fsnotify_add_inode_mark() wrappers fanotify: generalize fanotify_should_send_event() fsnotify: generalize send_to_group() fsnotify: generalize iteration of marks by object type fsnotify: introduce marks iteration helpers fsnotify: remove redundant arguments to handle_event() fsnotify: use type id to identify connector object type
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git://github.com/bzolnier/linux由 Linus Torvalds 提交于
Pull fbdev updates from Bartlomiej Zolnierkiewicz: "There is nothing really major here, few small fixes, some cleanups and dead drivers removal: - mark omapfb drivers as orphans in MAINTAINERS file (Tomi Valkeinen) - add missing module license tags to omap/omapfb driver (Arnd Bergmann) - add missing GPIOLIB dependendy to omap2/omapfb driver (Arnd Bergmann) - convert savagefb, aty128fb & radeonfb drivers to use msleep & co. (Jia-Ju Bai) - allow COMPILE_TEST build for viafb driver (media part was reviewed by media subsystem Maintainer) - remove unused MERAM support from sh_mobile_lcdcfb and shmob-drm drivers (drm parts were acked by shmob-drm driver Maintainer) - remove unused auo_k190xfb drivers - misc cleanups (Souptick Joarder, Wolfram Sang, Markus Elfring, Andy Shevchenko, Colin Ian King)" * tag 'fbdev-v4.18' of git://github.com/bzolnier/linux: (26 commits) fb_omap2: add gpiolib dependency video/omap: add module license tags MAINTAINERS: make omapfb orphan video: fbdev: pxafb: match_string() conversion fixup video: fbdev: nvidia: fix spelling mistake: "scaleing" -> "scaling" video: fbdev: fix spelling mistake: "frambuffer" -> "framebuffer" video: fbdev: pxafb: Convert to use match_string() helper video: fbdev: via: allow COMPILE_TEST build video: fbdev: remove unused sh_mobile_meram driver drm: shmobile: remove unused MERAM support video: fbdev: sh_mobile_lcdcfb: remove unused MERAM support video: fbdev: remove unused auo_k190xfb drivers video: omap: Improve a size determination in omapfb_do_probe() video: sm501fb: Improve a size determination in sm501fb_probe() video: fbdev-MMP: Improve a size determination in path_init() video: fbdev-MMP: Delete an error message for a failed memory allocation in two functions video: auo_k190x: Delete an error message for a failed memory allocation in auok190x_common_probe() video: sh_mobile_lcdcfb: Delete an error message for a failed memory allocation in two functions video: sh_mobile_meram: Delete an error message for a failed memory allocation in sh_mobile_meram_probe() video: fbdev: sh_mobile_meram: Drop SUPERH platform dependency ...
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