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  1. Jun 07, 2022
    • Alexey Kardashevskiy's avatar
      KVM: Don't null dereference ops->destroy · e8bc2427
      Alexey Kardashevskiy authored 
      

A KVM device cleanup happens in either of two callbacks:
1) destroy() which is called when the VM is being destroyed;
2) release() which is called when a device fd is closed.

Most KVM devices use 1) but Book3s's interrupt controller KVM devices
(XICS, XIVE, XIVE-native) use 2) as they need to close and reopen during
the machine execution. The error handling in kvm_ioctl_create_device()
assumes destroy() is always defined which leads to NULL dereference as
discovered by Syzkaller.

This adds a checks for destroy!=NULL and adds a missing release().

This is not changing kvm_destroy_devices() as devices with defined
release() should have been removed from the KVM devices list by then.

Suggested-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      e8bc2427
  3. May 25, 2022
    • Yanfei Xu's avatar
      KVM: x86: Fix the intel_pt PMI handling wrongly considered from guest · ffd1925a
      Yanfei Xu authored 
      When kernel handles the vm-exit caused by external interrupts and NMI,
it always sets kvm_intr_type to tell if it's dealing an IRQ or NMI. For
the PMI scenario, it could be IRQ or NMI.

However, intel_pt PMIs are only generated for HARDWARE perf events, and
HARDWARE events are always configured to generate NMIs.  Use
kvm_handling_nmi_from_guest() to precisely identify if the intel_pt PMI
came from the guest; this avoids false positives if an intel_pt PMI/NMI
arrives while the host is handling an unrelated IRQ VM-Exit.

Fixes: db215756

 ("KVM: x86: More precisely identify NMI from guest when handling PMI")
Signed-off-by: default avatarYanfei Xu <yanfei.xu@intel.com>
Message-Id: <20220523140821.1345605-1-yanfei.xu@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      ffd1925a
    • Like Xu's avatar
      KVM: selftests: x86: Sync the new name of the test case to .gitignore · 366d4a12
      Like Xu authored 
      

Fixing side effect of the so-called opportunistic change in the commit.

Fixes: dc8a9febbab0 ("KVM: selftests: x86: Fix test failure on arch lbr capable platforms")
Signed-off-by: default avatarLike Xu <likexu@tencent.com>
Message-Id: <20220518170118.66263-2-likexu@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      366d4a12
    • Paolo Bonzini's avatar
      Documentation: kvm: reorder ARM-specific section about KVM_SYSTEM_EVENT_SUSPEND · 186af6bb
      Paolo Bonzini authored 
      

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      186af6bb
    • Paolo Bonzini's avatar
      x86, kvm: use correct GFP flags for preemption disabled · baec4f5a
      Paolo Bonzini authored 
      

Commit ddd7ed842627 ("x86/kvm: Alloc dummy async #PF token outside of
raw spinlock") leads to the following Smatch static checker warning:

	arch/x86/kernel/kvm.c:212 kvm_async_pf_task_wake()
	warn: sleeping in atomic context

arch/x86/kernel/kvm.c
    202         raw_spin_lock(&b->lock);
    203         n = _find_apf_task(b, token);
    204         if (!n) {
    205                 /*
    206                  * Async #PF not yet handled, add a dummy entry for the token.
    207                  * Allocating the token must be down outside of the raw lock
    208                  * as the allocator is preemptible on PREEMPT_RT kernels.
    209                  */
    210                 if (!dummy) {
    211                         raw_spin_unlock(&b->lock);
--> 212                         dummy = kzalloc(sizeof(*dummy), GFP_KERNEL);
                                                                ^^^^^^^^^^
Smatch thinks the caller has preempt disabled.  The `smdb.py preempt
kvm_async_pf_task_wake` output call tree is:

sysvec_kvm_asyncpf_interrupt() <- disables preempt
-> __sysvec_kvm_asyncpf_interrupt()
   -> kvm_async_pf_task_wake()

The caller is this:

arch/x86/kernel/kvm.c
   290        DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
   291        {
   292                struct pt_regs *old_regs = set_irq_regs(regs);
   293                u32 token;
   294
   295                ack_APIC_irq();
   296
   297                inc_irq_stat(irq_hv_callback_count);
   298
   299                if (__this_cpu_read(apf_reason.enabled)) {
   300                        token = __this_cpu_read(apf_reason.token);
   301                        kvm_async_pf_task_wake(token);
   302                        __this_cpu_write(apf_reason.token, 0);
   303                        wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
   304                }
   305
   306                set_irq_regs(old_regs);
   307        }

The DEFINE_IDTENTRY_SYSVEC() is a wrapper that calls this function
from the call_on_irqstack_cond().  It's inside the call_on_irqstack_cond()
where preempt is disabled (unless it's already disabled).  The
irq_enter/exit_rcu() functions disable/enable preempt.

Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      baec4f5a
    • Wanpeng Li's avatar
      KVM: LAPIC: Drop pending LAPIC timer injection when canceling the timer · 619f51da
      Wanpeng Li authored 
      The timer is disarmed when switching between TSC deadline and other modes;
however, the pending timer is still in-flight, so let's accurately remove
any traces of the previous mode.

Fixes: 44275932

 ("KVM: x86: thoroughly disarm LAPIC timer around TSC deadline switch")
Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      619f51da
    • Sean Christopherson's avatar
      x86/kvm: Alloc dummy async #PF token outside of raw spinlock · 0547758a
      Sean Christopherson authored 
      

Drop the raw spinlock in kvm_async_pf_task_wake() before allocating the
the dummy async #PF token, the allocator is preemptible on PREEMPT_RT
kernels and must not be called from truly atomic contexts.

Opportunistically document why it's ok to loop on allocation failure,
i.e. why the function won't get stuck in an infinite loop.

Reported-by: default avatarYajun Deng <yajun.deng@linux.dev>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      0547758a
    • Sean Christopherson's avatar
      KVM: x86: avoid calling x86 emulator without a decoded instruction · fee060cd
      Sean Christopherson authored 
      Whenever x86_decode_emulated_instruction() detects a breakpoint, it
returns the value that kvm_vcpu_check_breakpoint() writes into its
pass-by-reference second argument.  Unfortunately this is completely
bogus because the expected outcome of x86_decode_emulated_instruction
is an EMULATION_* value.

Then, if kvm_vcpu_check_breakpoint() does "*r = 0" (corresponding to
a KVM_EXIT_DEBUG userspace exit), it is misunderstood as EMULATION_OK
and x86_emulate_instruction() is called without having decoded the
instruction.  This causes various havoc from running with a stale
emulation context.

The fix is to move the call to kvm_vcpu_check_breakpoint() where it was
before commit 4aa2691d

 ("KVM: x86: Factor out x86 instruction
emulation with decoding") introduced x86_decode_emulated_instruction().
The other caller of the function does not need breakpoint checks,
because it is invoked as part of a vmexit and the processor has already
checked those before executing the instruction that #GP'd.

This fixes CVE-2022-1852.

Reported-by: default avatarQiuhao Li <qiuhao@sysec.org>
Reported-by: default avatarGaoning Pan <pgn@zju.edu.cn>
Reported-by: default avatarYongkang Jia <kangel@zju.edu.cn>
Fixes: 4aa2691d

 ("KVM: x86: Factor out x86 instruction emulation with decoding")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20220311032801.3467418-2-seanjc@google.com>
[Rewrote commit message according to Qiuhao's report, since a patch
 already existed to fix the bug. - Paolo]
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      fee060cd
    • Ashish Kalra's avatar
      KVM: SVM: Use kzalloc for sev ioctl interfaces to prevent kernel data leak · d22d2474
      Ashish Kalra authored 
      

For some sev ioctl interfaces, the length parameter that is passed maybe
less than or equal to SEV_FW_BLOB_MAX_SIZE, but larger than the data
that PSP firmware returns. In this case, kmalloc will allocate memory
that is the size of the input rather than the size of the data.
Since PSP firmware doesn't fully overwrite the allocated buffer, these
sev ioctl interface may return uninitialized kernel slab memory.

Reported-by: default avatarAndy Nguyen <theflow@google.com>
Suggested-by: default avatarDavid Rientjes <rientjes@google.com>
Suggested-by: default avatarPeter Gonda <pgonda@google.com>
Cc: kvm@vger.kernel.org
Cc: stable@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Fixes: eaf78265 ("KVM: SVM: Move SEV code to separate file")
Fixes: 2c07ded0 ("KVM: SVM: add support for SEV attestation command")
Fixes: 4cfdd47d ("KVM: SVM: Add KVM_SEV SEND_START command")
Fixes: d3d1af85 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command")
Fixes: eba04b20

 ("KVM: x86: Account a variety of miscellaneous allocations")
Signed-off-by: default avatarAshish Kalra <ashish.kalra@amd.com>
Reviewed-by: default avatarPeter Gonda <pgonda@google.com>
Message-Id: <20220516154310.3685678-1-Ashish.Kalra@amd.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      d22d2474
    • Sean Christopherson's avatar
      x86/fpu: KVM: Set the base guest FPU uABI size to sizeof(struct kvm_xsave) · d187ba53
      Sean Christopherson authored 
      Set the starting uABI size of KVM's guest FPU to 'struct kvm_xsave',
i.e. to KVM's historical uABI size.  When saving FPU state for usersapce,
KVM (well, now the FPU) sets the FP+SSE bits in the XSAVE header even if
the host doesn't support XSAVE.  Setting the XSAVE header allows the VM
to be migrated to a host that does support XSAVE without the new host
having to handle FPU state that may or may not be compatible with XSAVE.

Setting the uABI size to the host's default size results in out-of-bounds
writes (setting the FP+SSE bits) and data corruption (that is thankfully
caught by KASAN) when running on hosts without XSAVE, e.g. on Core2 CPUs.

WARN if the default size is larger than KVM's historical uABI size; all
features that can push the FPU size beyond the historical size must be
opt-in.

  ==================================================================
  BUG: KASAN: slab-out-of-bounds in fpu_copy_uabi_to_guest_fpstate+0x86/0x130
  Read of size 8 at addr ffff888011e33a00 by task qemu-build/681
  CPU: 1 PID: 681 Comm: qemu-build Not tainted 5.18.0-rc5-KASAN-amd64 #1
  Hardware name:  /DG35EC, BIOS ECG3510M.86A.0118.2010.0113.1426 01/13/2010
  Call Trace:
   <TASK>
   dump_stack_lvl+0x34/0x45
   print_report.cold+0x45/0x575
   kasan_report+0x9b/0xd0
   fpu_copy_uabi_to_guest_fpstate+0x86/0x130
   kvm_arch_vcpu_ioctl+0x72a/0x1c50 [kvm]
   kvm_vcpu_ioctl+0x47f/0x7b0 [kvm]
   __x64_sys_ioctl+0x5de/0xc90
   do_syscall_64+0x31/0x50
   entry_SYSCALL_64_after_hwframe+0x44/0xae
   </TASK>
  Allocated by task 0:
  (stack is not available)
  The buggy address belongs to the object at ffff888011e33800
   which belongs to the cache kmalloc-512 of size 512
  The buggy address is located 0 bytes to the right of
   512-byte region [ffff888011e33800, ffff888011e33a00)
  The buggy address belongs to the physical page:
  page:0000000089cd4adb refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11e30
  head:0000000089cd4adb order:2 compound_mapcount:0 compound_pincount:0
  flags: 0x4000000000010200(slab|head|zone=1)
  raw: 4000000000010200 dead000000000100 dead000000000122 ffff888001041c80
  raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
  page dumped because: kasan: bad access detected
  Memory state around the buggy address:
   ffff888011e33900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
   ffff888011e33980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  >ffff888011e33a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                     ^
   ffff888011e33a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
   ffff888011e33b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ==================================================================
  Disabling lock debugging due to kernel taint

Fixes: be50b206 ("kvm: x86: Add support for getting/setting expanded xstate buffer")
Fixes: c60427dd

 ("x86/fpu: Add uabi_size to guest_fpu")
Reported-by: default avatarZdenek Kaspar <zkaspar82@gmail.com>
Cc: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Tested-by: default avatarZdenek Kaspar <zkaspar82@gmail.com>
Message-Id: <20220504001219.983513-1-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      d187ba53
    • Paolo Bonzini's avatar
      s390/uv_uapi: depend on CONFIG_S390 · eb3de2d8
      Paolo Bonzini authored 
      

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      eb3de2d8
    • Paolo Bonzini's avatar
      Merge tag 'kvm-s390-next-5.19-1' of... · 1644e270
      Paolo Bonzini authored 
      Merge tag 'kvm-s390-next-5.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: Fix and feature for 5.19

- ultravisor communication device driver
- fix TEID on terminating storage key ops
      1644e270
    • Paolo Bonzini's avatar
      Merge tag 'kvm-riscv-5.19-1' of https://github.com/kvm-riscv/linux into HEAD · b699da3d
      Paolo Bonzini authored 
      KVM/riscv changes for 5.19

- Added Sv57x4 support for G-stage page table
- Added range based local HFENCE functions
- Added remote HFENCE functions based on VCPU requests
- Added ISA extension registers in ONE_REG interface
- Updated KVM RISC-V maintainers entry to cover selftests support
      b699da3d
    • Paolo Bonzini's avatar
      Merge tag 'kvmarm-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD · 47e8eec8
      Paolo Bonzini authored 
      KVM/arm64 updates for 5.19

- Add support for the ARMv8.6 WFxT extension

- Guard pages for the EL2 stacks

- Trap and emulate AArch32 ID registers to hide unsupported features

- Ability to select and save/restore the set of hypercalls exposed
  to the guest

- Support for PSCI-initiated suspend in collaboration with userspace

- GICv3 register-based LPI invalidation support

- Move host PMU event merging into the vcpu data structure

- GICv3 ITS save/restore fixes

- The usual set of small-scale cleanups and fixes

[Due to the conflict, KVM_SYSTEM_EVENT_SEV_TERM is relocated
 from 4 to 6. - Paolo]
      47e8eec8
    • Yang Weijiang's avatar
      KVM: selftests: x86: Fix test failure on arch lbr capable platforms · 825be3b5
      Yang Weijiang authored 
      

On Arch LBR capable platforms, LBR_FMT in perf capability msr is 0x3f,
so the last format test will fail. Use a true invalid format(0x30) for
the test if it's running on these platforms. Opportunistically change
the file name to reflect the tests actually carried out.

Suggested-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarYang Weijiang <weijiang.yang@intel.com>
Message-Id: <20220512084046.105479-1-weijiang.yang@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      825be3b5
    • Wanpeng Li's avatar
      KVM: LAPIC: Trace LAPIC timer expiration on every vmentry · e0ac5351
      Wanpeng Li authored 
      In commit ec0671d5 ("KVM: LAPIC: Delay trace_kvm_wait_lapic_expire
tracepoint to after vmexit", 2019-06-04), trace_kvm_wait_lapic_expire
was moved after guest_exit_irqoff() because invoking tracepoints within
kvm_guest_enter/kvm_guest_exit caused a lockdep splat.

These days this is not necessary, because commit 87fa7f3e

 ("x86/kvm:
Move context tracking where it belongs", 2020-07-09) restricted
the RCU extended quiescent state to be closer to vmentry/vmexit.
Moving the tracepoint back to __kvm_wait_lapic_expire is more accurate,
because it will be reported even if vcpu_enter_guest causes multiple
vmentries via the IPI/Timer fast paths, and it allows the removal of
advance_expire_delta.

Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
Message-Id: <1650961551-38390-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      e0ac5351
  5. May 20, 2022
  7. May 17, 2022
    • Marc Zyngier's avatar
      Merge branch kvm-arm64/its-save-restore-fixes-5.19 into kvmarm-master/next · 5c0ad551
      Marc Zyngier authored 
      

* kvm-arm64/its-save-restore-fixes-5.19:
  : .
  : Tighten the ITS save/restore infrastructure to fail early rather
  : than late. Patches courtesy of Rocardo Koller.
  : .
  KVM: arm64: vgic: Undo work in failed ITS restores
  KVM: arm64: vgic: Do not ignore vgic_its_restore_cte failures
  KVM: arm64: vgic: Add more checks when restoring ITS tables
  KVM: arm64: vgic: Check that new ITEs could be saved in guest memory

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
      5c0ad551
    • Marc Zyngier's avatar
      Merge branch kvm-arm64/misc-5.19 into kvmarm-master/next · 822ca7f8
      Marc Zyngier authored 
      

* kvm-arm64/misc-5.19:
  : .
  : Misc fixes and general improvements for KVMM/arm64:
  :
  : - Better handle out of sequence sysregs in the global tables
  :
  : - Remove a couple of unnecessary loads from constant pool
  :
  : - Drop unnecessary pKVM checks
  :
  : - Add all known M1 implementations to the SEIS workaround
  :
  : - Cleanup kerneldoc warnings
  : .
  KVM: arm64: vgic-v3: List M1 Pro/Max as requiring the SEIS workaround
  KVM: arm64: pkvm: Don't mask already zeroed FEAT_SVE
  KVM: arm64: pkvm: Drop unnecessary FP/SIMD trap handler
  KVM: arm64: nvhe: Eliminate kernel-doc warnings
  KVM: arm64: Avoid unnecessary absolute addressing via literals
  KVM: arm64: Print emulated register table name when it is unsorted
  KVM: arm64: Don't BUG_ON() if emulated register table is unsorted

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
      822ca7f8
    • Marc Zyngier's avatar
      Merge branch kvm-arm64/per-vcpu-host-pmu-data into kvmarm-master/next · 8794b4f5
      Marc Zyngier authored 
      

* kvm-arm64/per-vcpu-host-pmu-data:
  : .
  : Pass the host PMU state in the vcpu to avoid the use of additional
  : shared memory between EL1 and EL2 (this obviously only applies
  : to nVHE and Protected setups).
  :
  : Patches courtesy of Fuad Tabba.
  : .
  KVM: arm64: pmu: Restore compilation when HW_PERF_EVENTS isn't selected
  KVM: arm64: Reenable pmu in Protected Mode
  KVM: arm64: Pass pmu events to hyp via vcpu
  KVM: arm64: Repack struct kvm_pmu to reduce size
  KVM: arm64: Wrapper for getting pmu_events

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
      8794b4f5
    • Marc Zyngier's avatar
      Merge branch kvm-arm64/vgic-invlpir into kvmarm-master/next · ec2cff6c
      Marc Zyngier authored 
      

* kvm-arm64/vgic-invlpir:
  : .
  : Implement MMIO-based LPI invalidation for vGICv3.
  : .
  KVM: arm64: vgic-v3: Advertise GICR_CTLR.{IR, CES} as a new GICD_IIDR revision
  KVM: arm64: vgic-v3: Implement MMIO-based LPI invalidation
  KVM: arm64: vgic-v3: Expose GICR_CTLR.RWP when disabling LPIs
  irqchip/gic-v3: Exposes bit values for GICR_CTLR.{IR, CES}

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
      ec2cff6c
    • Marc Zyngier's avatar
      Merge branch kvm-arm64/psci-suspend into kvmarm-master/next · 3b8e21e3
      Marc Zyngier authored 
      

* kvm-arm64/psci-suspend:
  : .
  : Add support for PSCI SYSTEM_SUSPEND and allow userspace to
  : filter the wake-up events.
  :
  : Patches courtesy of Oliver.
  : .
  Documentation: KVM: Fix title level for PSCI_SUSPEND
  selftests: KVM: Test SYSTEM_SUSPEND PSCI call
  selftests: KVM: Refactor psci_test to make it amenable to new tests
  selftests: KVM: Use KVM_SET_MP_STATE to power off vCPU in psci_test
  selftests: KVM: Create helper for making SMCCC calls
  selftests: KVM: Rename psci_cpu_on_test to psci_test
  KVM: arm64: Implement PSCI SYSTEM_SUSPEND
  KVM: arm64: Add support for userspace to suspend a vCPU
  KVM: arm64: Return a value from check_vcpu_requests()
  KVM: arm64: Rename the KVM_REQ_SLEEP handler
  KVM: arm64: Track vCPU power state using MP state values
  KVM: arm64: Dedupe vCPU power off helpers
  KVM: arm64: Don't depend on fallthrough to hide SYSTEM_RESET2

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
      3b8e21e3
    • Marc Zyngier's avatar
      Merge branch kvm-arm64/hcall-selection into kvmarm-master/next · 0586e28a
      Marc Zyngier authored 
      

* kvm-arm64/hcall-selection:
  : .
  : Introduce a new set of virtual sysregs for userspace to
  : select the hypercalls it wants to see exposed to the guest.
  :
  : Patches courtesy of Raghavendra and Oliver.
  : .
  KVM: arm64: Fix hypercall bitmap writeback when vcpus have already run
  KVM: arm64: Hide KVM_REG_ARM_*_BMAP_BIT_COUNT from userspace
  Documentation: Fix index.rst after psci.rst renaming
  selftests: KVM: aarch64: Add the bitmap firmware registers to get-reg-list
  selftests: KVM: aarch64: Introduce hypercall ABI test
  selftests: KVM: Create helper for making SMCCC calls
  selftests: KVM: Rename psci_cpu_on_test to psci_test
  tools: Import ARM SMCCC definitions
  Docs: KVM: Add doc for the bitmap firmware registers
  Docs: KVM: Rename psci.rst to hypercalls.rst
  KVM: arm64: Add vendor hypervisor firmware register
  KVM: arm64: Add standard hypervisor firmware register
  KVM: arm64: Setup a framework for hypercall bitmap firmware registers
  KVM: arm64: Factor out firmware register handling from psci.c

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
      0586e28a
    • Marc Zyngier's avatar
      KVM: arm64: Fix hypercall bitmap writeback when vcpus have already run · 528ada28
      Marc Zyngier authored 
      We generally want to disallow hypercall bitmaps being changed
once vcpus have already run. But we must allow the write if
the written value is unchanged so that userspace can rewrite
the register file on reboot, for example.

Without this, a QEMU-based VM will fail to reboot correctly.

The original code was correct, and it is me that introduced
the regression.

Fixes: 05714cab

 ("KVM: arm64: Setup a framework for hypercall bitmap firmware registers")
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
      528ada28
  9. May 16, 2022