The IMO, FMO and AMO bits in HCR_EL2 are defined to "behave as
1 for all purposes other than direct reads" if HCR_EL2.TGE
is set and HCR_EL2.E2H is 0, and to "behave as 0 for all
purposes other than direct reads" if HCR_EL2.TGE is set
and HRC_EL2.E2H is 1.

To avoid having to check E2H and TGE everywhere where we test IMO and
FMO, provide accessors arm_hcr_el2_imo(), arm_hcr_el2_fmo()and
arm_hcr_el2_amo().  We don't implement ARMv8.1-VHE yet, so the E2H
case will never be true, but we include the logic to save effort when
we eventually do get to that.

(Note that in several of these callsites the change doesn't
actually make a difference as either the callsite is handling
TGE specially anyway, or the CPU can't get into that situation
with TGE set; we change everywhere for consistency.)
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Message-id: 20180724115950.17316-5-peter.maydell@linaro.org

Whene we raise a synchronous exception, if HCR_EL2.TGE is set then
exceptions targeting NS EL1 must be redirected to EL2.  Implement
this in raise_exception() -- all synchronous exceptions go through
this function.

(Asynchronous exceptions go via arm_cpu_exec_interrupt(), which
already honours HCR_EL2.TGE when it determines the target EL
in arm_phys_excp_target_el().)
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Message-id: 20180724115950.17316-4-peter.maydell@linaro.org

Some debug registers can be trapped via MDCR_EL2 bits TDRA, TDOSA,
and TDA, which we implement in the functions access_tdra(),
access_tdosa() and access_tda(). If MDCR_EL2.TDE or HCR_EL2.TGE
are 1, the TDRA, TDOSA and TDA bits should behave as if they were 1.
Implement this by having the access functions check MDCR_EL2.TDE
and HCR_EL2.TGE.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Message-id: 20180724115950.17316-3-peter.maydell@linaro.org

If the "trap general exceptions" bit HCR_EL2.TGE is set, we
must mask all virtual interrupts (as per DDI0487C.a D1.14.3).
Implement this in arm_excp_unmasked().
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Message-id: 20180724115950.17316-2-peter.maydell@linaro.org

Use an int64_t as a return type to restore
the negative check for arm_load_as.
Signed-off-by: NAdam Lackorzynski <adam@l4re.org>
Message-id: 20180730173712.GG4987@os.inf.tu-dresden.de
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Add support for GICv2 virtualization extensions by mapping the necessary
I/O regions and connecting the maintenance IRQ lines.

Declare those additions in the device tree and in the ACPI tables.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-21-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

This commit improve the way the GIC is realized and connected in the
ZynqMP SoC. The security extensions are enabled only if requested in the
machine state. The same goes for the virtualization extensions.

All the GIC to APU CPU(s) IRQ lines are now connected, including FIQ,
vIRQ and vFIQ. The missing CPU to GIC timers IRQ connections are also
added (HYP and SEC timers).

The GIC maintenance IRQs are back-wired to the correct GIC PPIs.

Finally, the MMIO mappings are reworked to take into account the ZynqMP
specifics. The GIC (v)CPU interface is aliased 16 times:
  * for the first 0x1000 bytes from 0xf9010000 to 0xf901f000
  * for the second 0x1000 bytes from 0xf9020000 to 0xf902f000
Mappings of the virtual interface and virtual CPU interface are mapped
only when virtualization extensions are requested. The
XlnxZynqMPGICRegion struct has been enhanced to be able to catch all
this information.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NEdgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 20180727095421.386-20-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Add some traces to the ARM GIC to catch register accesses (distributor,
(v)cpu interface and virtual interface), and to take into account
virtualization extensions (print `vcpu` instead of `cpu` when needed).

Also add some virtualization extensions specific traces: LR updating
and maintenance IRQ generation.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-19-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Implement the maintenance interrupt generation that is part of the GICv2
virtualization extensions.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-18-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Add the gic_update_virt() function to update the vCPU interface states
and raise vIRQ and vFIQ as needed. This commit renames gic_update() to
gic_update_internal() and generalizes it to handle both cases, with a
`virt' parameter to track whether we are updating the CPU or vCPU
interfaces.

The main difference between CPU and vCPU is the way we select the best
IRQ. This part has been split into the gic_get_best_(v)irq functions.
For the virt case, the LRs are iterated to find the best candidate.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-17-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Implement the read and write functions for the virtual interface of the
virtualization extensions in the GICv2.

One mirror region per CPU is also created, which maps to that specific
CPU id. This is required by the GIC architecture specification.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-16-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Add the read/write functions to handle accesses to the vCPU interface.
Those accesses are forwarded to the real CPU interface, with the CPU id
being converted to the corresponding vCPU id (vCPU id = CPU id +
GIC_NCPU).
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Message-id: 20180727095421.386-15-luc.michel@greensocs.com
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Implement virtualization extensions in the gic_cpu_read() and
gic_cpu_write() functions. Those are the last bits missing to fully
support virtualization extensions in the CPU interface path.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-14-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Implement virtualization extensions in the gic_deactivate_irq() and
gic_complete_irq() functions.

When the guest writes an invalid vIRQ to V_EOIR or V_DIR, since the
GICv2 specification is not entirely clear here, we adopt the behaviour
observed on real hardware:
  * When V_CTRL.EOIMode is false (EOI split is disabled):
    - In case of an invalid vIRQ write to V_EOIR:
      -> If some bits are set in H_APR, an invalid vIRQ write to V_EOIR
         triggers a priority drop, and increments V_HCR.EOICount.
      -> If V_APR is already cleared, nothing happen

    - An invalid vIRQ write to V_DIR is ignored.

  * When V_CTRL.EOIMode is true:
    - In case of an invalid vIRQ write to V_EOIR:
      -> If some bits are set in H_APR, an invalid vIRQ write to V_EOIR
         triggers a priority drop.
      -> If V_APR is already cleared, nothing happen

    - An invalid vIRQ write to V_DIR increments V_HCR.EOICount.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Message-id: 20180727095421.386-13-luc.michel@greensocs.com
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Implement virtualization extensions in the gic_acknowledge_irq()
function. This function changes the state of the highest priority IRQ
from pending to active.

When the current CPU is a vCPU, modifying the state of an IRQ modifies
the corresponding LR entry. However if we clear the pending flag before
setting the active one, we lose track of the LR entry as it becomes
invalid. The next call to gic_get_lr_entry() will fail.

To overcome this issue, we call gic_activate_irq() before
gic_clear_pending(). This does not change the general behaviour of
gic_acknowledge_irq.

We also move the SGI case in gic_clear_pending_sgi() to enhance
code readability as the virtualization extensions support adds a if-else
level.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-12-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Implement virtualization extensions in gic_activate_irq() and
gic_drop_prio() and in gic_get_prio_from_apr_bits() called by
gic_drop_prio().

When the current CPU is a vCPU:
  - Use GIC_VIRT_MIN_BPR and GIC_VIRT_NR_APRS instead of their non-virt
  counterparts,
  - the vCPU APR is stored in the virtual interface, in h_apr.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-11-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Add some helper functions to gic_internal.h to get or change the state
of an IRQ. When the current CPU is not a vCPU, the call is forwarded to
the GIC distributor. Otherwise, it acts on the list register matching
the IRQ in the current CPU virtual interface.

gic_clear_active can have a side effect on the distributor, even in the
vCPU case, when the correponding LR has the HW field set.

Use those functions in the CPU interface code path to prepare for the
vCPU interface implementation.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180727095421.386-10-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

An access to the CPU interface is non-secure if the current GIC instance
implements the security extensions, and the memory access is actually
non-secure. Until then, it was checked with tests such as
  if (s->security_extn && !attrs.secure) { ... }
in various places of the CPU interface code.

With the implementation of the virtualization extensions, those tests
must be updated to take into account whether we are in a vCPU interface
or not. This is because the exposed vCPU interface does not implement
security extensions.

This commits replaces all those tests with a call to the
gic_cpu_ns_access() function to check if the current access to the CPU
interface is non-secure. This function takes into account whether the
current CPU is a vCPU or not.

Note that this function is used only in the (v)CPU interface code path.
The distributor code path is left unchanged, as the distributor is not
exposed to vCPUs at all.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180727095421.386-9-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Add some helper macros and functions related to the virtualization
extensions to gic_internal.h.

The GICH_LR_* macros help extracting specific fields of a list register
value. The only tricky one is the priority field as only the MSB are
stored. The value must be shifted accordingly to obtain the correct
priority value.

gic_is_vcpu() and gic_get_vcpu_real_id() help with (v)CPU id manipulation
to abstract the fact that vCPU id are in the range
[ GIC_NCPU; (GIC_NCPU + num_cpu) [.

gic_lr_* and gic_virq_is_valid() help with the list registers.
gic_get_lr_entry() returns the LR entry for a given (vCPU, irq) pair. It
is meant to be used in contexts where we know for sure that the entry
exists, so we assert that entry is actually found, and the caller can
avoid the NULL check on the returned pointer.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-8-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Add the register definitions for the virtual interface of the GICv2.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-7-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Add the necessary parts of the virtualization extensions state to the
GIC state. We choose to increase the size of the CPU interfaces state to
add space for the vCPU interfaces (the GIC_NCPU_VCPU macro). This way,
we'll be able to reuse most of the CPU interface code for the vCPUs.

The only exception is the APR value, which is stored in h_apr in the
virtual interface state for vCPUs. This is due to some complications
with the GIC VMState, for which we don't want to break backward
compatibility. APRs being stored in 2D arrays, increasing the second
dimension would lead to some ugly VMState description. To avoid
that, we keep it in h_apr for vCPUs.

The vCPUs are numbered from GIC_NCPU to (GIC_NCPU * 2) - 1. The
`gic_is_vcpu` function help to determine if a given CPU id correspond to
a physical CPU or a virtual one.

For the in-kernel KVM VGIC, since the exposed VGIC does not implement
the virtualization extensions, we report an error if the corresponding
property is set to true.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-6-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Provide a VMSTATE_UINT16_SUB_ARRAY macro to save a uint16_t sub-array in
a VMState.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180727095421.386-5-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Some functions are now only used in arm_gic.c, put them static. Some of
them where only used by the NVIC implementation and are not used
anymore, so remove them.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-4-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Implement GICD_ISACTIVERn and GICD_ICACTIVERn registers in the GICv2.
Those registers allow to set or clear the active state of an IRQ in the
distributor.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-3-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

In preparation for the virtualization extensions implementation,
refactor the name of the functions and macros that act on the GIC
distributor to make that fact explicit. It will be useful to
differentiate them from the ones that will act on the virtual
interfaces.
Signed-off-by: NLuc Michel <luc.michel@greensocs.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NSai Pavan Boddu <sai.pavan.boddu@xilinx.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 20180727095421.386-2-luc.michel@greensocs.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

We set up TLB entries in tlb_set_page_with_attrs(), where we have
some logic for determining whether the TLB entry is considered
to be RAM-backed, and thus has a valid addend field. When we
look at the TLB entry in get_page_addr_code(), we use different
logic for determining whether to treat the page as RAM-backed
and use the addend field. This is confusing, and in fact buggy,
because the code in tlb_set_page_with_attrs() correctly decides
that rom_device memory regions not in romd mode are not RAM-backed,
but the code in get_page_addr_code() thinks they are RAM-backed.
This typically results in "Bad ram pointer" assertion if the
guest tries to execute from such a memory region.

Fix this by making get_page_addr_code() just look at the
TLB_MMIO bit in the code_address field of the TLB, which
tlb_set_page_with_attrs() sets if and only if the addend
field is not valid for code execution.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Tested-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180713150945.12348-1-peter.maydell@linaro.org

Now that we have full support for small regions, including execution,
we can remove the workarounds where we marked all small regions as
non-executable for the M-profile MPU and SAU.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: NCédric Le Goater <clg@kaod.org>
Tested-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180710160013.26559-7-peter.maydell@linaro.org

Now that all the callers can handle get_page_addr_code() returning -1,
remove all the code which tries to handle execution from MMIO regions
or small-MMU-region RAM areas. This will mean that we can correctly
execute from these areas, rather than ending up either aborting QEMU
or delivering an incorrect guest exception.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: NCédric Le Goater <clg@kaod.org>
Tested-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180710160013.26559-6-peter.maydell@linaro.org

If get_page_addr_code() returns -1, this indicates that there is no RAM
page we can read a full TB from. Instead we must create a TB which
contains a single instruction and which we do not cache, so it is
executed only once.

Since this means we can now have TBs which are not in any page list,
we also need to make tb_phys_invalidate() handle them (by not trying
to remove them from a nonexistent page list).
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: NEmilio G. Cota <cota@braap.org>
Tested-by: NCédric Le Goater <clg@kaod.org>
Message-id: 20180710160013.26559-5-peter.maydell@linaro.org

When we support execution from non-RAM MMIO regions, get_page_addr_code()
will return -1 to indicate that there is no RAM at the requested address.
Handle this in tb_check_watchpoint() -- if the exception happened for a
PC which doesn't correspond to RAM then there is no need to invalidate
any TBs, because the one-instruction TB will not have been cached.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Tested-by: NCédric Le Goater <clg@kaod.org>
Message-id: 20180710160013.26559-4-peter.maydell@linaro.org

When we support execution from non-RAM MMIO regions, get_page_addr_code()
will return -1 to indicate that there is no RAM at the requested address.
Handle this in the cpu-exec TB hashtable lookup code, treating it as
"no match found".

Note that the call to get_page_addr_code() in tb_lookup_cmp() needs
no changes -- a return of -1 will already correctly result in the
function returning false.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: NEmilio G. Cota <cota@braap.org>
Tested-by: NCédric Le Goater <clg@kaod.org>
Message-id: 20180710160013.26559-3-peter.maydell@linaro.org

The io_readx() function needs to know whether the load it is
doing is an MMU_DATA_LOAD or an MMU_INST_FETCH, so that it
can pass the right value to the cpu_transaction_failed()
function. Plumb this information through from the softmmu
code.

This is currently not often going to give the wrong answer,
because usually instruction fetches go via get_page_addr_code().
However once we switch over to handling execution from non-RAM by
creating single-insn TBs, the path for an insn fetch to generate
a bus error will be through cpu_ld*_code() and io_readx(),
so without this change we will generate a d-side fault when we
should generate an i-side fault.

We also have to pass the access type via a CPU struct global
down to unassigned_mem_read(), for the benefit of the targets
which still use the cpu_unassigned_access() hook (m68k, mips,
sparc, xtensa).
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: NCédric Le Goater <clg@kaod.org>
Message-id: 20180710160013.26559-2-peter.maydell@linaro.org

The differences from ARMv7-M NVIC are:
  * ARMv6-M only supports up to 32 external interrupts
   (configurable feature already). The ICTR is reserved.
  * Active Bit Register is reserved.
  * ARMv6-M supports 4 priority levels against 256 in ARMv7-M.
Signed-off-by: NJulia Suvorova <jusual@mail.ru>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Forbid stack alignment change. (CCR)
Reserve FAULTMASK, BASEPRI registers.
Report any fault as a HardFault. Disable MemManage, BusFault and
UsageFault, so they always escalated to HardFault. (SHCSR)
Signed-off-by: NJulia Suvorova <jusual@mail.ru>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 20180718095628.26442-1-jusual@mail.ru
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Handle SCS reserved registers listed in ARMv6-M ARM D3.6.1.
All reserved registers are RAZ/WI. ARM_FEATURE_M_MAIN is used for the
checks, because these registers are reserved in ARMv8-M Baseline too.
Signed-off-by: NJulia Suvorova <jusual@mail.ru>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

MSR handling is the only place where CONTROL.nPRIV is modified.
Signed-off-by: NJulia Suvorova <jusual@mail.ru>
Message-id: 20180705222622.17139-1-jusual@mail.ru
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

With vga=775 on the Linux command line a first boot of the VM running
Linux works fine. After a warm reboot it crashes during Linux boot.

Before that, valgrind points out bad memory write to console
surface. The VGA code is not aware that virtio-gpu got a message
surface scanout when the display is disabled. Let's reset VGA graphic
mode when it is the case, so that a new display surface is created
when doing further VGA operations.

https://bugs.launchpad.net/qemu/+bug/1784900/Reported-by: NStefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NGerd Hoffmann <kraxel@redhat.com>
Tested-by: NStefan Berger <stefanb@linux.vnet.ibm.com>
Message-id: 20180803153235.4134-1-marcandre.lureau@redhat.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

The data in an mbuf buffer is not necessarily at the start of the
allocated buffer. (For instance m_adj() allows data to be trimmed
from the start by just advancing the pointer and reducing the length.)
This means that the allocated buffer size (m->m_size) and the
amount of space from the m_data pointer to the end of the
buffer (M_ROOM(m)) are not necessarily the same.

Commit 864036e2 tried to change the m_inc() function from
taking the new allocated-buffer-size to taking the new room-size,
but forgot to change the initial "do we already have enough space"
check. This meant that if we were trying to extend a buffer which
had a leading gap between the buffer start and the data, we might
incorrectly decide it didn't need to be extended, and then
overrun the end of the buffer, causing memory corruption and
an eventual crash.

Change the "already big enough?" condition from checking the
argument against m->m_size to checking against M_ROOM().
This only makes a difference for the callsite in m_cat();
the other three callsites all start with a freshly allocated
mbuf from m_get(), which will have m->m_size == M_ROOM(m).

Fixes: 864036e2
Fixes: https://bugs.launchpad.net/qemu/+bug/1785670Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NSamuel Thibault <samuel.thibault@ens-lyon.org>
Message-id: 20180807114501.12370-1-peter.maydell@linaro.org
Tested-by: NDr. David Alan Gilbert <dgilbert@redhat.com>