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916987 Commits

Author SHA1 Message Date
Jon Doron
f7d31e6536 x86/kvm/hyper-v: Explicitly align hcall param for kvm_hyperv_exit
The problem the patch is trying to address is the fact that 'struct
kvm_hyperv_exit' has different layout on when compiling in 32 and 64 bit
modes.

In 64-bit mode the default alignment boundary is 64 bits thus
forcing extra gaps after 'type' and 'msr' but in 32-bit mode the
boundary is at 32 bits thus no extra gaps.

This is an issue as even when the kernel is 64 bit, the userspace using
the interface can be both 32 and 64 bit but the same 32 bit userspace has
to work with 32 bit kernel.

The issue is fixed by forcing the 64 bit layout, this leads to ABI
change for 32 bit builds and while we are obviously breaking '32 bit
userspace with 32 bit kernel' case, we're fixing the '32 bit userspace
with 64 bit kernel' one.

As the interface has no (known) users and 32 bit KVM is rather baroque
nowadays, this seems like a reasonable decision.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Jon Doron <arilou@gmail.com>
Message-Id: <20200424113746.3473563-2-arilou@gmail.com>
Reviewed-by: Roman Kagan <rvkagan@yandex-team.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:09 -04:00
Like Xu
27461da310 KVM: x86/pmu: Support full width counting
Intel CPUs have a new alternative MSR range (starting from MSR_IA32_PMC0)
for GP counters that allows writing the full counter width. Enable this
range from a new capability bit (IA32_PERF_CAPABILITIES.FW_WRITE[bit 13]).

The guest would query CPUID to get the counter width, and sign extends
the counter values as needed. The traditional MSRs always limit to 32bit,
even though the counter internally is larger (48 or 57 bits).

When the new capability is set, use the alternative range which do not
have these restrictions. This lowers the overhead of perf stat slightly
because it has to do less interrupts to accumulate the counter value.

Signed-off-by: Like Xu <like.xu@linux.intel.com>
Message-Id: <20200529074347.124619-3-like.xu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:09 -04:00
Wei Wang
cbd717585b KVM: x86/pmu: Tweak kvm_pmu_get_msr to pass 'struct msr_data' in
Change kvm_pmu_get_msr() to get the msr_data struct, as the host_initiated
field from the struct could be used by get_msr. This also makes this API
consistent with kvm_pmu_set_msr. No functional changes.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Message-Id: <20200529074347.124619-2-like.xu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:08 -04:00
Vitaly Kuznetsov
72de5fa4c1 KVM: x86: announce KVM_FEATURE_ASYNC_PF_INT
Introduce new capability to indicate that KVM supports interrupt based
delivery of 'page ready' APF events. This includes support for both
MSR_KVM_ASYNC_PF_INT and MSR_KVM_ASYNC_PF_ACK.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200525144125.143875-8-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:08 -04:00
Vitaly Kuznetsov
557a961abb KVM: x86: acknowledgment mechanism for async pf page ready notifications
If two page ready notifications happen back to back the second one is not
delivered and the only mechanism we currently have is
kvm_check_async_pf_completion() check in vcpu_run() loop. The check will
only be performed with the next vmexit when it happens and in some cases
it may take a while. With interrupt based page ready notification delivery
the situation is even worse: unlike exceptions, interrupts are not handled
immediately so we must check if the slot is empty. This is slow and
unnecessary. Introduce dedicated MSR_KVM_ASYNC_PF_ACK MSR to communicate
the fact that the slot is free and host should check its notification
queue. Mandate using it for interrupt based 'page ready' APF event
delivery.

As kvm_check_async_pf_completion() is going away from vcpu_run() we need
a way to communicate the fact that vcpu->async_pf.done queue has
transitioned from empty to non-empty state. Introduce
kvm_arch_async_page_present_queued() and KVM_REQ_APF_READY to do the job.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200525144125.143875-7-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:08 -04:00
Vitaly Kuznetsov
2635b5c4a0 KVM: x86: interrupt based APF 'page ready' event delivery
Concerns were expressed around APF delivery via synthetic #PF exception as
in some cases such delivery may collide with real page fault. For 'page
ready' notifications we can easily switch to using an interrupt instead.
Introduce new MSR_KVM_ASYNC_PF_INT mechanism and deprecate the legacy one.

One notable difference between the two mechanisms is that interrupt may not
get handled immediately so whenever we would like to deliver next event
(regardless of its type) we must be sure the guest had read and cleared
previous event in the slot.

While on it, get rid on 'type 1/type 2' names for APF events in the
documentation as they are causing confusion. Use 'page not present'
and 'page ready' everywhere instead.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200525144125.143875-6-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:07 -04:00
Vitaly Kuznetsov
0958f0cefe KVM: introduce kvm_read_guest_offset_cached()
We already have kvm_write_guest_offset_cached(), introduce read analogue.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200525144125.143875-5-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:07 -04:00
Vitaly Kuznetsov
7c0ade6c90 KVM: rename kvm_arch_can_inject_async_page_present() to kvm_arch_can_dequeue_async_page_present()
An innocent reader of the following x86 KVM code:

bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu)
{
        if (!(vcpu->arch.apf.msr_val & KVM_ASYNC_PF_ENABLED))
                return true;
...

may get very confused: if APF mechanism is not enabled, why do we report
that we 'can inject async page present'? In reality, upon injection
kvm_arch_async_page_present() will check the same condition again and,
in case APF is disabled, will just drop the item. This is fine as the
guest which deliberately disabled APF doesn't expect to get any APF
notifications.

Rename kvm_arch_can_inject_async_page_present() to
kvm_arch_can_dequeue_async_page_present() to make it clear what we are
checking: if the item can be dequeued (meaning either injected or just
dropped).

On s390 kvm_arch_can_inject_async_page_present() always returns 'true' so
the rename doesn't matter much.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200525144125.143875-4-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:07 -04:00
Vitaly Kuznetsov
68fd66f100 KVM: x86: extend struct kvm_vcpu_pv_apf_data with token info
Currently, APF mechanism relies on the #PF abuse where the token is being
passed through CR2. If we switch to using interrupts to deliver page-ready
notifications we need a different way to pass the data. Extent the existing
'struct kvm_vcpu_pv_apf_data' with token information for page-ready
notifications.

While on it, rename 'reason' to 'flags'. This doesn't change the semantics
as we only have reasons '1' and '2' and these can be treated as bit flags
but KVM_PV_REASON_PAGE_READY is going away with interrupt based delivery
making 'reason' name misleading.

The newly introduced apf_put_user_ready() temporary puts both flags and
token information, this will be changed to put token only when we switch
to interrupt based notifications.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200525144125.143875-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:06 -04:00
Vitaly Kuznetsov
84b09f33a5 Revert "KVM: async_pf: Fix #DF due to inject "Page not Present" and "Page Ready" exceptions simultaneously"
Commit 9a6e7c3981 (""KVM: async_pf: Fix #DF due to inject "Page not
Present" and "Page Ready" exceptions simultaneously") added a protection
against 'page ready' notification coming before 'page not present' is
delivered. This situation seems to be impossible since commit 2a266f2355
("KVM MMU: check pending exception before injecting APF) which added
'vcpu->arch.exception.pending' check to kvm_can_do_async_pf.

On x86, kvm_arch_async_page_present() has only one call site:
kvm_check_async_pf_completion() loop and we only enter the loop when
kvm_arch_can_inject_async_page_present(vcpu) which when async pf msr
is enabled, translates into kvm_can_do_async_pf().

There is also one problem with the cancellation mechanism. We don't seem
to check that the 'page not present' notification we're canceling matches
the 'page ready' notification so in theory, we may erroneously drop two
valid events.

Revert the commit.

Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200525144125.143875-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:06 -04:00
Gustavo A. R. Silva
f4a9fdd5f1 KVM: VMX: Replace zero-length array with flexible-array
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Message-Id: <20200507185618.GA14831@embeddedor>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:05 -04:00
Paolo Bonzini
a8387d0b47 Revert "KVM: No need to retry for hva_to_pfn_remapped()"
This reverts commit 5b494aea13.
If unlocked==true then the vma pointer could be invalidated, so the 2nd
follow_pfn() is potentially racy: we do need to get out and redo
find_vma_intersection().

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:05 -04:00
Paolo Bonzini
cc440cdad5 KVM: nSVM: implement KVM_GET_NESTED_STATE and KVM_SET_NESTED_STATE
Similar to VMX, the state that is captured through the currently available
IOCTLs is a mix of L1 and L2 state, dependent on whether the L2 guest was
running at the moment when the process was interrupted to save its state.

In particular, the SVM-specific state for nested virtualization includes
the L1 saved state (including the interrupt flag), the cached L2 controls,
and the GIF.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:05 -04:00
Vitaly Kuznetsov
8ec107c89b selftests: kvm: fix smm test on SVM
KVM_CAP_NESTED_STATE is now supported for AMD too but smm test acts like
it is still Intel only.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200529130407.57176-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:04 -04:00
Paolo Bonzini
10b910cb7e selftests: kvm: add a SVM version of state-test
The test is similar to the existing one for VMX, but simpler because we
don't have to test shadow VMCS or vmptrld/vmptrst/vmclear.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:04 -04:00
Vitaly Kuznetsov
ed88129733 selftests: kvm: introduce cpu_has_svm() check
Many tests will want to check if the CPU is Intel or AMD in
guest code, add cpu_has_svm() and put it as static
inline to svm_util.h.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200529130407.57176-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:04 -04:00
Paolo Bonzini
929d1cfaa6 KVM: MMU: pass arbitrary CR0/CR4/EFER to kvm_init_shadow_mmu
This allows fetching the registers from the hsave area when setting
up the NPT shadow MMU, and is needed for KVM_SET_NESTED_STATE (which
runs long after the CR0, CR4 and EFER values in vcpu have been switched
to hold L2 guest state).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:03 -04:00
Paolo Bonzini
c513f484c5 KVM: nSVM: leave guest mode when clearing EFER.SVME
According to the AMD manual, the effect of turning off EFER.SVME while a
guest is running is undefined.  We make it leave guest mode immediately,
similar to the effect of clearing the VMX bit in MSR_IA32_FEAT_CTL.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:03 -04:00
Paolo Bonzini
ca46d739e3 KVM: nSVM: split nested_vmcb_check_controls
The authoritative state does not come from the VMCB once in guest mode,
but KVM_SET_NESTED_STATE can still perform checks on L1's provided SVM
controls because we get them from userspace.

Therefore, split out a function to do them.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:03 -04:00
Paolo Bonzini
08245e6d2e KVM: nSVM: remove HF_HIF_MASK
The L1 flags can be found in the save area of svm->nested.hsave, fish
it from there so that there is one fewer thing to migrate.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:02 -04:00
Paolo Bonzini
e9fd761a46 KVM: nSVM: remove HF_VINTR_MASK
Now that the int_ctl field is stored in svm->nested.ctl.int_ctl, we can
use it instead of vcpu->arch.hflags to check whether L2 is running
in V_INTR_MASKING mode.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:02 -04:00
Paolo Bonzini
36e2e98363 KVM: nSVM: synthesize correct EXITINTINFO on vmexit
This bit was added to nested VMX right when nested_run_pending was
introduced, but it is not yet there in nSVM.  Since we can have pending
events that L0 injected directly into L2 on vmentry, we have to transfer
them into L1's queue.

For this to work, one important change is required: svm_complete_interrupts
(which clears the "injected" fields from the previous VMRUN, and updates them
from svm->vmcb's EXITINTINFO) must be placed before we inject the vmexit.
This is not too scary though; VMX even does it in vmx_vcpu_run.

While at it, the nested_vmexit_inject tracepoint is moved towards the
end of nested_svm_vmexit.  This ensures that the synthesized EXITINTINFO
is visible in the trace.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:02 -04:00
Paolo Bonzini
91b7130cb6 KVM: SVM: preserve VGIF across VMCB switch
There is only one GIF flag for the whole processor, so make sure it is not clobbered
when switching to L2 (in which case we also have to include the V_GIF_ENABLE_MASK,
lest we confuse enable_gif/disable_gif/gif_set).  When going back, L1 could in
theory have entered L2 without issuing a CLGI so make sure the svm_set_gif is
done last, after svm->vmcb->control.int_ctl has been copied back from hsave.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:01 -04:00
Paolo Bonzini
ffdf7f9e80 KVM: nSVM: extract svm_set_gif
Extract the code that is needed to implement CLGI and STGI,
so that we can run it from VMRUN and vmexit (and in the future,
KVM_SET_NESTED_STATE).  Skip the request for KVM_REQ_EVENT unless needed,
subsuming the evaluate_pending_interrupts optimization that is found
in enter_svm_guest_mode.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:01 -04:00
Paolo Bonzini
31031098fe KVM: nSVM: remove unnecessary if
kvm_vcpu_apicv_active must be false when nested virtualization is enabled,
so there is no need to check it in clgi_interception.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:01 -04:00
Paolo Bonzini
2d8a42be0e KVM: nSVM: synchronize VMCB controls updated by the processor on every vmexit
The control state changes on every L2->L0 vmexit, and we will have to
serialize it in the nested state.  So keep it up to date in svm->nested.ctl
and just copy them back to the nested VMCB in nested_svm_vmexit.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:00 -04:00
Paolo Bonzini
d8e4e58f4b KVM: nSVM: restore clobbered INT_CTL fields after clearing VINTR
Restore the INT_CTL value from the guest's VMCB once we've stopped using
it, so that virtual interrupts can be injected as requested by L1.
V_TPR is up-to-date however, and it can change if the guest writes to CR8,
so keep it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:00 -04:00
Paolo Bonzini
e670bf68f4 KVM: nSVM: save all control fields in svm->nested
In preparation for nested SVM save/restore, store all data that matters
from the VMCB control area into svm->nested.  It will then become part
of the nested SVM state that is saved by KVM_SET_NESTED_STATE and
restored by KVM_GET_NESTED_STATE, just like the cached vmcs12 for nVMX.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:26:00 -04:00
Paolo Bonzini
7923ef4f6e KVM: nSVM: remove trailing padding for struct vmcb_control_area
Allow placing the VMCB structs on the stack or in other structs without
wasting too much space.  Add BUILD_BUG_ON as a quick safeguard against typos.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:25:59 -04:00
Paolo Bonzini
2f675917ef KVM: nSVM: pass vmcb_control_area to copy_vmcb_control_area
This will come in handy when we put a struct vmcb_control_area in
svm->nested.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:25:59 -04:00
Paolo Bonzini
18fc6c55d1 KVM: nSVM: clean up tsc_offset update
Use l1_tsc_offset to compute svm->vcpu.arch.tsc_offset and
svm->vmcb->control.tsc_offset, instead of relying on hsave.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:25:59 -04:00
Paolo Bonzini
69cb877487 KVM: nSVM: move MMU setup to nested_prepare_vmcb_control
Everything that is needed during nested state restore is now part of
nested_prepare_vmcb_control.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:25:58 -04:00
Paolo Bonzini
f241d711b2 KVM: nSVM: extract preparation of VMCB for nested run
Split out filling svm->vmcb.save and svm->vmcb.control before VMRUN.
Only the latter will be useful when restoring nested SVM state.

This patch introduces no semantic change, so the MMU setup is still
done in nested_prepare_vmcb_save.  The next patch will clean up things.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:25:58 -04:00
Paolo Bonzini
3e06f0163f KVM: nSVM: extract load_nested_vmcb_control
When restoring SVM nested state, the control state cache in svm->nested
will have to be filled, but the save state will not have to be moved
into svm->vmcb.  Therefore, pull the code that handles the control area
into a separate function.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:25:58 -04:00
Paolo Bonzini
69c9dfa24b KVM: nSVM: move map argument out of enter_svm_guest_mode
Unmapping the nested VMCB in enter_svm_guest_mode is a bit of a wart,
since the map argument is not used elsewhere in the function.  There are
just two callers, and those are also the place where kvm_vcpu_map is
called, so it is cleaner to unmap there.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-01 04:24:32 -04:00
Paolo Bonzini
df7e0681dd KVM: nVMX: always update CR3 in VMCS
vmx_load_mmu_pgd is delaying the write of GUEST_CR3 to prepare_vmcs02 as
an optimization, but this is only correct before the nested vmentry.
If userspace is modifying CR3 with KVM_SET_SREGS after the VM has
already been put in guest mode, the value of CR3 will not be updated.
Remove the optimization, which almost never triggers anyway.

Fixes: 04f11ef458 ("KVM: nVMX: Always write vmcs02.GUEST_CR3 during nested VM-Enter")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-28 11:46:18 -04:00
Paolo Bonzini
978ce5837c KVM: SVM: always update CR3 in VMCB
svm_load_mmu_pgd is delaying the write of GUEST_CR3 to prepare_vmcs02 as
an optimization, but this is only correct before the nested vmentry.
If userspace is modifying CR3 with KVM_SET_SREGS after the VM has
already been put in guest mode, the value of CR3 will not be updated.
Remove the optimization, which almost never triggers anyway.
This was was added in commit 689f3bf216 ("KVM: x86: unify callbacks
to load paging root", 2020-03-16) just to keep the two vendor-specific
modules closer, but we'll fix VMX too.

Fixes: 689f3bf216 ("KVM: x86: unify callbacks to load paging root")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-28 11:46:18 -04:00
Paolo Bonzini
5b67240866 KVM: nSVM: correctly inject INIT vmexits
The usual drill at this point, except there is no code to remove because this
case was not handled at all.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-28 11:46:18 -04:00
Paolo Bonzini
bd279629f7 KVM: nSVM: remove exit_required
All events now inject vmexits before vmentry rather than after vmexit.  Therefore,
exit_required is not set anymore and we can remove it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-28 11:46:17 -04:00
Paolo Bonzini
7c86663b68 KVM: nSVM: inject exceptions via svm_check_nested_events
This allows exceptions injected by the emulator to be properly delivered
as vmexits.  The code also becomes simpler, because we can just let all
L0-intercepted exceptions go through the usual path.  In particular, our
emulation of the VMX #DB exit qualification is very much simplified,
because the vmexit injection path can use kvm_deliver_exception_payload
to update DR6.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-28 11:46:17 -04:00
Paolo Bonzini
c9d40913ac KVM: x86: enable event window in inject_pending_event
In case an interrupt arrives after nested.check_events but before the
call to kvm_cpu_has_injectable_intr, we could end up enabling the interrupt
window even if the interrupt is actually going to be a vmexit.  This is
useless rather than harmful, but it really complicates reasoning about
SVM's handling of the VINTR intercept.  We'd like to never bother with
the VINTR intercept if V_INTR_MASKING=1 && INTERCEPT_INTR=1, because in
that case there is no interrupt window and we can just exit the nested
guest whenever we want.

This patch moves the opening of the interrupt window inside
inject_pending_event.  This consolidates the check for pending
interrupt/NMI/SMI in one place, and makes KVM's usage of immediate
exits more consistent, extending it beyond just nested virtualization.

There are two functional changes here.  They only affect corner cases,
but overall they simplify the inject_pending_event.

- re-injection of still-pending events will also use req_immediate_exit
instead of using interrupt-window intercepts.  This should have no impact
on performance on Intel since it simply replaces an interrupt-window
or NMI-window exit for a preemption-timer exit.  On AMD, which has no
equivalent of the preemption time, it may incur some overhead but an
actual effect on performance should only be visible in pathological cases.

- kvm_arch_interrupt_allowed and kvm_vcpu_has_events will return true
if an interrupt, NMI or SMI is blocked by nested_run_pending.  This
makes sense because entering the VM will allow it to make progress
and deliver the event.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-28 11:41:46 -04:00
Paolo Bonzini
c6b22f59d6 KVM: x86: track manually whether an event has been injected
Instead of calling kvm_event_needs_reinjection, track its
future return value in a variable.  This will be useful in
the next patch.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-27 13:11:12 -04:00
Vitaly Kuznetsov
b6162e82ae KVM: nSVM: Preserve registers modifications done before nested_svm_vmexit()
L2 guest hang is observed after 'exit_required' was dropped and nSVM
switched to check_nested_events() completely. The hang is a busy loop when
e.g. KVM is emulating an instruction (e.g. L2 is accessing MMIO space and
we drop to userspace). After nested_svm_vmexit() and when L1 is doing VMRUN
nested guest's RIP is not advanced so KVM goes into emulating the same
instruction which caused nested_svm_vmexit() and the loop continues.

nested_svm_vmexit() is not new, however, with check_nested_events() we're
now calling it later than before. In case by that time KVM has modified
register state we may pick stale values from VMCB when trying to save
nested guest state to nested VMCB.

nVMX code handles this case correctly: sync_vmcs02_to_vmcs12() called from
nested_vmx_vmexit() does e.g 'vmcs12->guest_rip = kvm_rip_read(vcpu)' and
this ensures KVM-made modifications are preserved. Do the same for nSVM.

Generally, nested_vmx_vmexit()/nested_svm_vmexit() need to pick up all
nested guest state modifications done by KVM after vmexit. It would be
great to find a way to express this in a way which would not require to
manually track these changes, e.g. nested_{vmcb,vmcs}_get_field().

Co-debugged-with: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200527090102.220647-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-27 13:11:12 -04:00
Sean Christopherson
7d2e8748af KVM: x86: Initialize tdp_level during vCPU creation
Initialize vcpu->arch.tdp_level during vCPU creation to avoid consuming
garbage if userspace calls KVM_RUN without first calling KVM_SET_CPUID.

Fixes: e93fd3b3e8 ("KVM: x86/mmu: Capture TDP level when updating CPUID")
Reported-by: syzbot+904752567107eefb728c@syzkaller.appspotmail.com
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200527085400.23759-1-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-27 13:11:11 -04:00
Paolo Bonzini
6c0238c4a6 KVM: nSVM: leave ASID aside in copy_vmcb_control_area
Restoring the ASID from the hsave area on VMEXIT is wrong, because its
value depends on the handling of TLB flushes.  Just skipping the field in
copy_vmcb_control_area will do.

Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-27 13:11:11 -04:00
Paolo Bonzini
a3535be731 KVM: nSVM: fix condition for filtering async PF
Async page faults have to be trapped in the host (L1 in this case),
since the APF reason was passed from L0 to L1 and stored in the L1 APF
data page.  This was completely reversed: the page faults were passed
to the guest, a L2 hypervisor.

Cc: stable@vger.kernel.org
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-27 13:11:10 -04:00
彭浩(Richard)
88197e6ab3 kvm/x86: Remove redundant function implementations
pic_in_kernel(), ioapic_in_kernel() and irqchip_kernel() have the
same implementation.

Signed-off-by: Peng Hao <richard.peng@oppo.com>
Message-Id: <HKAPR02MB4291D5926EA10B8BFE9EA0D3E0B70@HKAPR02MB4291.apcprd02.prod.outlook.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-27 13:11:10 -04:00
Haiwei Li
80bc97f2d8 KVM: Fix the indentation to match coding style
There is a bad indentation in next&queue branch. The patch looks like
fixes nothing though it fixes the indentation.

Before fixing:

                 if (!handle_fastpath_set_x2apic_icr_irqoff(vcpu, data)) {
                         kvm_skip_emulated_instruction(vcpu);
                         ret = EXIT_FASTPATH_EXIT_HANDLED;
                }
                 break;
         case MSR_IA32_TSCDEADLINE:

After fixing:

                 if (!handle_fastpath_set_x2apic_icr_irqoff(vcpu, data)) {
                         kvm_skip_emulated_instruction(vcpu);
                         ret = EXIT_FASTPATH_EXIT_HANDLED;
                 }
                 break;
         case MSR_IA32_TSCDEADLINE:

Signed-off-by: Haiwei Li <lihaiwei@tencent.com>
Message-Id: <2f78457e-f3a7-3bc9-e237-3132ee87f71e@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-27 13:11:09 -04:00
Miaohe Lin
a8cfbae592 KVM: VMX: replace "fall through" with "return" to indicate different case
The second "/* fall through */" in rmode_exception() makes code harder to
read. Replace it with "return" to indicate they are different cases, only
the #DB and #BP check vcpu->guest_debug, while others don't care. And this
also improves the readability.

Suggested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Message-Id: <1582080348-20827-1-git-send-email-linmiaohe@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-27 13:11:09 -04:00
Sean Christopherson
cb97c2d680 KVM: x86: Take an unsigned 32-bit int for has_emulated_msr()'s index
Take a u32 for the index in has_emulated_msr() to match hardware, which
treats MSR indices as unsigned 32-bit values.  Functionally, taking a
signed int doesn't cause problems with the current code base, but could
theoretically cause problems with 32-bit KVM, e.g. if the index were
checked via a less-than statement, which would evaluate incorrectly for
MSR indices with bit 31 set.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200218234012.7110-3-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-27 13:11:08 -04:00