Commit 3fa5e8fd ("KVM: SVM: delay svm_vcpu_init_msrpm after
svm->vmcb is initialized") re-arranged svm_vcpu_init_msrpm() call in
svm_create_vcpu(), thus making the comment about vmcb being NULL
obsolete. Drop it.

While on it, drop superfluous vmcb_is_clean() check: vmcb_mark_dirty()
is a bit flip, an extra check is unlikely to bring any performance gain.
Drop now-unneeded vmcb_is_clean() helper as well.

Fixes: 3fa5e8fd

 ("KVM: SVM: delay svm_vcpu_init_msrpm after svm->vmcb is initialized")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211220152139.418372-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Commit c4327f15 ("KVM: SVM: hyper-v: Enlightened MSR-Bitmap support")
introduced enlightened MSR-Bitmap support for KVM-on-Hyper-V but it didn't
actually enable the support. Similar to enlightened NPT TLB flush and
direct TLB flush features, the guest (KVM) has to tell L0 (Hyper-V) that
it's using the feature by setting the appropriate feature fit in VMCB
control area (sw reserved fields).

Fixes: c4327f15

 ("KVM: SVM: hyper-v: Enlightened MSR-Bitmap support")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211220152139.418372-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Inject a #GP instead of synthesizing triple fault to try to avoid killing
the guest if emulation of an SEV guest fails due to encountering the SMAP
erratum.  The injected #GP may still be fatal to the guest, e.g. if the
userspace process is providing critical functionality, but KVM should
make every attempt to keep the guest alive.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Message-Id: <20220120010719.711476-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Resume the guest instead of synthesizing a triple fault shutdown if the
instruction bytes buffer is empty due to the #NPF being on the code fetch
itself or on a page table access.  The SMAP errata applies if and only if
the code fetch was successful and ucode's subsequent data read from the
code page encountered a SMAP violation.  In practice, the guest is likely
hosed either way, but crashing the guest on a code fetch to emulated MMIO
is technically wrong according to the behavior described in the APM.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Message-Id: <20220120010719.711476-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Inject #UD if KVM attempts emulation for an SEV guests without an insn
buffer and instruction decoding is required.  The previous behavior of
allowing emulation if there is no insn buffer is undesirable as doing so
means KVM is reading guest private memory and thus decoding cyphertext,
i.e. is emulating garbage.  The check was previously necessary as the
emulation type was not provided, i.e. SVM needed to allow emulation to
handle completion of emulation after exiting to userspace to handle I/O.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Message-Id: <20220120010719.711476-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

WARN if KVM attempts to emulate in response to #UD or #GP for SEV guests,
i.e. if KVM intercepts #UD or #GP, as emulation on any fault except #NPF
is impossible since KVM cannot read guest private memory to get the code
stream, and the CPU's DecodeAssists feature only provides the instruction
bytes on #NPF.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Message-Id: <20220120010719.711476-7-seanjc@google.com>
[Warn on EMULTYPE_TRAP_UD_FORCED according to Liam Merwick's review. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Pass the emulation type to kvm_x86_ops.can_emulate_insutrction() so that
a future commit can harden KVM's SEV support to WARN on emulation
scenarios that should never happen.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Message-Id: <20220120010719.711476-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Add a sanity check on DECODEASSIST being support if SEV is supported, as
KVM cannot read guest private memory and thus relies on the CPU to
provide the instruction byte stream on #NPF for emulation.  The intent of
the check is to document the dependency, it should never fail in practice
as producing hardware that supports SEV but not DECODEASSISTS would be
non-sensical.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Message-Id: <20220120010719.711476-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Never intercept #GP for SEV guests as reading SEV guest private memory
will return cyphertext, i.e. emulating on #GP can't work as intended.

Cc: stable@vger.kernel.org
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Message-Id: <20220120010719.711476-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Revert a completely broken check on an "invalid" RIP in SVM's workaround
for the DecodeAssists SMAP errata.  kvm_vcpu_gfn_to_memslot() obviously
expects a gfn, i.e. operates in the guest physical address space, whereas
RIP is a virtual (not even linear) address.  The "fix" worked for the
problematic KVM selftest because the test identity mapped RIP.

Fully revert the hack instead of trying to translate RIP to a GPA, as the
non-SEV case is now handled earlier, and KVM cannot access guest page
tables to translate RIP.

This reverts commit e72436bc.

Fixes: e72436bc

 ("KVM: SVM: avoid infinite loop on NPF from bad address")
Reported-by: Liam Merwick <liam.merwick@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Message-Id: <20220120010719.711476-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Always signal that emulation is possible for !SEV guests regardless of
whether or not the CPU provided a valid instruction byte stream.  KVM can
read all guest state (memory and registers) for !SEV guests, i.e. can
fetch the code stream from memory even if the CPU failed to do so because
of the SMAP errata.

Fixes: 05d5a486

 ("KVM: SVM: Workaround errata#1096 (insn_len maybe zero on SMAP violation)")
Cc: stable@vger.kernel.org
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Message-Id: <20220120010719.711476-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The bug occurs on #GP triggered by VMware backdoor when eax value is
unaligned. eax alignment check should not be applied to non-SVM
instructions because it leads to incorrect omission of the instructions
emulation.
Apply the alignment check only to SVM instructions to fix.

Fixes: d1cba6c9

 ("KVM: x86: nSVM: test eax for 4K alignment for GP errata workaround")
Signed-off-by: Denis Valeev <lemniscattaden@gmail.com>
Message-Id: <Yexlhaoe1Fscm59u@q>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

With the help of xstate_get_guest_group_perm(), KVM can exclude unpermitted
xfeatures in cpuid.0xd.0.eax, in which case the corresponding xfeatures
sizes should also be matched to the permitted xfeatures.

To fix this inconsistency, the permitted_xcr0 and permitted_xss are defined
consistently, which implies 'supported' plus certain permissions for this
task, and it also fixes cpuid.0xd.1.ebx and later leaf-by-leaf queries.

Fixes: 445ecdf7

 ("kvm: x86: Exclude unpermitted xfeatures at KVM_GET_SUPPORTED_CPUID")
Signed-off-by: Like Xu <likexu@tencent.com>
Message-Id: <20220125115223.33707-1-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The below warning is splatting during guest reboot.

  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 1931 at arch/x86/kvm/x86.c:10322 kvm_arch_vcpu_ioctl_run+0x874/0x880 [kvm]
  CPU: 0 PID: 1931 Comm: qemu-system-x86 Tainted: G          I       5.17.0-rc1+ #5
  RIP: 0010:kvm_arch_vcpu_ioctl_run+0x874/0x880 [kvm]
  Call Trace:
   <TASK>
   kvm_vcpu_ioctl+0x279/0x710 [kvm]
   __x64_sys_ioctl+0x83/0xb0
   do_syscall_64+0x3b/0xc0
   entry_SYSCALL_64_after_hwframe+0x44/0xae
  RIP: 0033:0x7fd39797350b

This can be triggered by not exposing tsc-deadline mode and doing a reboot in
the guest. The lapic_shutdown() function which is called in sys_reboot path
will not disarm the flying timer, it just masks LVTT. lapic_shutdown() clears
APIC state w/ LVT_MASKED and timer-mode bit is 0, this can trigger timer-mode
switch between tsc-deadline and oneshot/periodic, which can result in preemption
timer be cancelled in apic_update_lvtt(). However, We can't depend on this when
not exposing tsc-deadline mode and oneshot/periodic modes emulated by preemption
timer. Qemu will synchronise states around reset, let's cancel preemption timer
under KVM_SET_LAPIC.

Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1643102220-35667-1-git-send-email-wanpengli@tencent.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The maximum size of a VMCS (or VMXON region) is 4096. By definition,
these are order 0 allocations.

Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <20220125004359.147600-1-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Make kvm_vcpu_reload_apic_access_page() static
as it is no longer invoked directly by vmx
and it is also no longer exported.

No functional change intended.

Signed-off-by: Quanfa Fu <quanfafu@gmail.com>
Message-Id: <20211219091446.174584-1-quanfafu@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This selftest was accidentally removed by commit 6a581508
("selftest: KVM: Add intra host migration tests"). Add it back.

Fixes: 6a581508

 ("selftest: KVM: Add intra host migration tests")
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220120003826.2805036-1-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Set vmcs.GUEST_PENDING_DBG_EXCEPTIONS.BS, a.k.a. the pending single-step
breakpoint flag, when re-injecting a #DB with RFLAGS.TF=1, and STI or
MOVSS blocking is active.  Setting the flag is necessary to make VM-Entry
consistency checks happy, as VMX has an invariant that if RFLAGS.TF is
set and STI/MOVSS blocking is true, then the previous instruction must
have been STI or MOV/POP, and therefore a single-step #DB must be pending
since the RFLAGS.TF cannot have been set by the previous instruction,
i.e. the one instruction delay after setting RFLAGS.TF must have already
expired.

Normally, the CPU sets vmcs.GUEST_PENDING_DBG_EXCEPTIONS.BS appropriately
when recording guest state as part of a VM-Exit, but #DB VM-Exits
intentionally do not treat the #DB as "guest state" as interception of
the #DB effectively makes the #DB host-owned, thus KVM needs to manually
set PENDING_DBG.BS when forwarding/re-injecting the #DB to the guest.

Note, although this bug can be triggered by guest userspace, doing so
requires IOPL=3, and guest userspace running with IOPL=3 has full access
to all I/O ports (from the guest's perspective) and can crash/reboot the
guest any number of ways.  IOPL=3 is required because STI blocking kicks
in if and only if RFLAGS.IF is toggled 0=>1, and if CPL>IOPL, STI either
takes a #GP or modifies RFLAGS.VIF, not RFLAGS.IF.

MOVSS blocking can be initiated by userspace, but can be coincident with
a #DB if and only if DR7.GD=1 (General Detect enabled) and a MOV DR is
executed in the MOVSS shadow.  MOV DR #GPs at CPL>0, thus MOVSS blocking
is problematic only for CPL0 (and only if the guest is crazy enough to
access a DR in a MOVSS shadow).  All other sources of #DBs are either
suppressed by MOVSS blocking (single-step, code fetch, data, and I/O),
are mutually exclusive with MOVSS blocking (T-bit task switch), or are
already handled by KVM (ICEBP, a.k.a. INT1).

This bug was originally found by running tests[1] created for XSA-308[2].
Note that Xen's userspace test emits ICEBP in the MOVSS shadow, which is
presumably why the Xen bug was deemed to be an exploitable DOS from guest
userspace.  KVM already handles ICEBP by skipping the ICEBP instruction
and thus clears MOVSS blocking as a side effect of its "emulation".

[1] http://xenbits.xenproject.org/docs/xtf/xsa-308_2main_8c_source.html
[2] https://xenbits.xen.org/xsa/advisory-308.html



Reported-by: David Woodhouse <dwmw2@infradead.org>
Reported-by: Alexander Graf <graf@amazon.de>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220120000624.655815-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Full equality check of CPUID data on update (kvm_cpuid_check_equal()) may
fail for SGX enabled CPUs as CPUID.(EAX=0x12,ECX=1) is currently being
mangled in kvm_vcpu_after_set_cpuid(). Move it to
__kvm_update_cpuid_runtime() and split off cpuid_get_supported_xcr0()
helper  as 'vcpu->arch.guest_supported_xcr0' update needs (logically)
to stay in kvm_vcpu_after_set_cpuid().

Cc: stable@vger.kernel.org
Fixes: feb627e8

 ("KVM: x86: Forbid KVM_SET_CPUID{,2} after KVM_RUN")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220124103606.2630588-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The async parameter of hva_to_pfn_remapped() is not used, so remove it.

Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
Message-Id: <20220124020456.156386-1-xianting.tian@linux.alibaba.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Commit 14243b38 ("KVM: x86/xen: Add KVM_IRQ_ROUTING_XEN_EVTCHN and
event channel delivery") adds superfluous .fixup usage after the whole
.fixup section was removed in commit e5eefda5 ("x86: Remove .fixup
section").

Fixes: 14243b38

 ("KVM: x86/xen: Add KVM_IRQ_ROUTING_XEN_EVTCHN and event channel delivery")
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Message-Id: <20220123124219.GH20638@worktop.programming.kicks-ass.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Zero vmcs.HOST_IA32_SYSENTER_ESP when initializing *constant* host state
if and only if SYSENTER cannot be used, i.e. the kernel is a 64-bit
kernel and is not emulating 32-bit syscalls.  As the name suggests,
vmx_set_constant_host_state() is intended for state that is *constant*.
When SYSENTER is used, SYSENTER_ESP isn't constant because stacks are
per-CPU, and the VMCS must be updated whenever the vCPU is migrated to a
new CPU.  The logic in vmx_vcpu_load_vmcs() doesn't differentiate between
"never loaded" and "loaded on a different CPU", i.e. setting SYSENTER_ESP
on VMCS load also handles setting correct host state when the VMCS is
first loaded.

Because a VMCS must be loaded before it is initialized during vCPU RESET,
zeroing the field in vmx_set_constant_host_state() obliterates the value
that was written when the VMCS was loaded.  If the vCPU is run before it
is migrated, the subsequent VM-Exit will zero out MSR_IA32_SYSENTER_ESP,
leading to a #DF on the next 32-bit syscall.

  double fault: 0000 [#1] SMP
  CPU: 0 PID: 990 Comm: stable Not tainted 5.16.0+ #97
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
  EIP: entry_SYSENTER_32+0x0/0xe7
  Code: <9c> 50 eb 17 0f 20 d8 a9 00 10 00 00 74 0d 25 ff ef ff ff 0f 22 d8
  EAX: 000000a2 EBX: a8d1300c ECX: a8d13014 EDX: 00000000
  ESI: a8f87000 EDI: a8d13014 EBP: a8d12fc0 ESP: 00000000
  DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 EFLAGS: 00210093
  CR0: 80050033 CR2: fffffffc CR3: 02c3b000 CR4: 00152e90

Fixes: 6ab8a405

 ("KVM: VMX: Avoid to rdmsrl(MSR_IA32_SYSENTER_ESP)")
Cc: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220122015211.1468758-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Use the api number 134 for KVM_GET_XSAVE2, instead of 42, which has been
used by KVM_GET_XSAVE.
Also, fix the WARNINGs of the underlines being too short.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Tested-by: Stephen Rothwell <sfr@canb.auug.org.au>
Message-Id: <20220120045003.315177-1-wei.w.wang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The following warning appears when executing
make -C tools/testing/selftests/kvm

include/x86_64/processor.h:290:2: warning: 'ecx' may be used uninitialized in this
function [-Wmaybe-uninitialized]
  asm volatile("cpuid"
  ^~~
lib/x86_64/processor.c:1523:21: note: 'ecx' was declared here
  uint32_t eax, ebx, ecx, edx, max_ext_leaf;

Just initialize ecx to remove this warning.

Fixes: c8cc43c1

 ("selftests: KVM: avoid failures due to reserved HyperTransport region")
Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Message-Id: <20220119140325.59369-1-cloudliang@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The following warning appears when executing
make -C tools/testing/selftests/kvm

x86_64/pmu_event_filter_test.c: In function 'vcpu_supports_intel_br_retired':
x86_64/pmu_event_filter_test.c:241:28: warning: variable 'cpuid' set but not used [-Wunused-but-set-variable]
  241 |         struct kvm_cpuid2 *cpuid;
      |                            ^~~~~
x86_64/pmu_event_filter_test.c: In function 'vcpu_supports_amd_zen_br_retired':
x86_64/pmu_event_filter_test.c:258:28: warning: variable 'cpuid' set but not used [-Wunused-but-set-variable]
  258 |         struct kvm_cpuid2 *cpuid;
      |                            ^~~~~

Just delete the unused variables to stay away from warnings.

Fixes: dc7e75b3b3ee ("selftests: kvm/x86: Add test for KVM_SET_PMU_EVENT_FILTER")
Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Message-Id: <20220119133910.56285-1-cloudliang@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Some indentation with spaces crept in, likely due to terminal-based
cut and paste.  Clean it up.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM_CAP_XSAVE2 is out of sync due to a conflict.  Copy the whole
file while at it.

Reported-by: Yang Zhong <yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

amx_test's binary should be present in the .gitignore file for the git
to ignore it.

Fixes: bf70636d

 ("selftest: kvm: Add amx selftest")
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Message-Id: <20220118122053.1941915-1-usama.anjum@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Nullify svm_x86_ops.vcpu_(un)blocking if AVIC/APICv is disabled as the
hooks are necessary only to clear the vCPU's IsRunning entry in the
Physical APIC and to update IRTE entries if the VM has a pass-through
device attached.

Opportunistically rename the helpers to clarify their AVIC relationship.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-24-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Move svm_hardware_setup() below svm_x86_ops so that KVM can modify ops
during setup, e.g. the vcpu_(un)blocking hooks can be nullified if AVIC
is disabled or unsupported.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-23-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Drop avic_set_running() in favor of calling avic_vcpu_{load,put}()
directly, and modify the block+put path to use preempt_disable/enable()
instead of get/put_cpu(), as it doesn't actually care about the current
pCPU associated with the vCPU.  Opportunistically add lockdep assertions
as being preempted in avic_vcpu_put() would lead to consuming stale data,
even though doing so _in the current code base_ would not be fatal.

Add a much needed comment explaining why svm_vcpu_blocking() needs to
unload the AVIC and update the IRTE _before_ the vCPU starts blocking.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-22-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

When waking vCPUs in the posted interrupt wakeup handling, do exactly
that and no more.  There is no need to kick the vCPU as the wakeup
handler just needs to get the vCPU task running, and if it's in the guest
then it's definitely running.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211208015236.1616697-21-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Move the fallback "wake_up" path into the helper to trigger posted
interrupt helper now that the nested and non-nested paths are identical.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211208015236.1616697-20-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Refactor the posted interrupt helper to take the desired notification
vector instead of a bool so that the callers are self-documenting.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211208015236.1616697-19-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Replace the full "kick" with just the "wake" in the fallback path when
triggering a virtual interrupt via a posted interrupt fails because the
guest is not IN_GUEST_MODE.  If the guest transitions into guest mode
between the check and the kick, then it's guaranteed to see the pending
interrupt as KVM syncs the PIR to IRR (and onto GUEST_RVI) after setting
IN_GUEST_MODE.  Kicking the guest in this case is nothing more than an
unnecessary VM-Exit (and host IRQ).

Opportunistically update comments to explain the various ordering rules
and barriers at play.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Don't bother updating the Physical APIC table or IRTE when loading a vCPU
that is blocking, i.e. won't be marked IsRun{ning}=1, as the pCPU is
queried if and only if IsRunning is '1'.  If the vCPU was migrated, the
new pCPU will be picked up when avic_vcpu_load() is called by
svm_vcpu_unblocking().

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-15-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Use kvm_vcpu_is_blocking() to determine whether or not the vCPU should be
marked running during avic_vcpu_load().  Drop avic_is_running, which
really should have been named "vcpu_is_not_blocking", as it tracked if
the vCPU was blocking, not if it was actually running, e.g. it was set
during svm_create_vcpu() when the vCPU was obviously not running.

This is technically a teeny tiny functional change, as the vCPU will be
marked IsRunning=1 on being reloaded if the vCPU is preempted between
svm_vcpu_blocking() and prepare_to_rcuwait().  But that's a benign change
as the vCPU will be marked IsRunning=0 when KVM voluntarily schedules out
the vCPU.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Remove handling of KVM_REQ_APICV_UPDATE from svm_vcpu_unblocking(), it's
no longer needed as it was made obsolete by commit df7e4827

 ("KVM:
SVM: call avic_vcpu_load/avic_vcpu_put when enabling/disabling AVIC").
Prior to that commit, the manual check was necessary to ensure the AVIC
stuff was updated by avic_set_running() when a request to enable APICv
became pending while the vCPU was blocking, as the request handling
itself would not do the update.  But, as evidenced by the commit, that
logic was flawed and subject to various races.

Now that svm_refresh_apicv_exec_ctrl() does avic_vcpu_load/put() in
response to an APICv status change, drop the manual check in the
unblocking path.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-13-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Drop the avic_vcpu_is_running() check when waking vCPUs in response to a
VM-Exit due to incomplete IPI delivery.  The check isn't wrong per se, but
it's not 100% accurate in the sense that it doesn't guarantee that the vCPU
was one of the vCPUs that didn't receive the IPI.

The check isn't required for correctness as blocking == !running in this
context.

From a performance perspective, waking a live task is not expensive as the
only moderately costly operation is a locked operation to temporarily
disable preemption.  And if that is indeed a performance issue,
kvm_vcpu_is_blocking() would be a better check than poking into the AVIC.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211208015236.1616697-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signal the AVIC doorbell iff the vCPU is running in the guest.  If the vCPU
is not IN_GUEST_MODE, it's guaranteed to pick up any pending IRQs on the
next VMRUN, which unconditionally processes the vIRR.

Add comments to document the logic.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-11-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>