Right now, the VMX preemption timer is special cased via the
hv_timer_pending, but the purpose of the callback can be easily
extended to observing any event that can occur only in non-root
mode. Interrupts, NMIs etc. are already handled properly by
the *_interrupt_allowed callbacks, so what is missing is only
MTF. Check it in the newly-renamed callback, so that
kvm_vcpu_running's call to kvm_check_nested_events
becomes redundant.
Cc: [email protected]
Reported-by: Maxim Levitsky <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/vmx/nested.c | 7 ++++++-
arch/x86/kvm/x86.c | 8 ++++----
3 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4ff36610af6a..e2e4f60159e9 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1504,7 +1504,7 @@ struct kvm_x86_ops {
struct kvm_x86_nested_ops {
void (*leave_nested)(struct kvm_vcpu *vcpu);
int (*check_events)(struct kvm_vcpu *vcpu);
- bool (*hv_timer_pending)(struct kvm_vcpu *vcpu);
+ bool (*has_events)(struct kvm_vcpu *vcpu);
void (*triple_fault)(struct kvm_vcpu *vcpu);
int (*get_state)(struct kvm_vcpu *vcpu,
struct kvm_nested_state __user *user_kvm_nested_state,
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 856c87563883..54672025c3a1 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3857,6 +3857,11 @@ static bool nested_vmx_preemption_timer_pending(struct kvm_vcpu *vcpu)
to_vmx(vcpu)->nested.preemption_timer_expired;
}
+static bool vmx_has_nested_events(struct kvm_vcpu *vcpu)
+{
+ return nested_vmx_preemption_timer_pending(vcpu) || vmx->nested.mtf_pending;
+}
+
static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -6809,7 +6814,7 @@ __init int nested_vmx_hardware_setup(int (*exit_handlers[])(struct kvm_vcpu *))
struct kvm_x86_nested_ops vmx_nested_ops = {
.leave_nested = vmx_leave_nested,
.check_events = vmx_check_nested_events,
- .hv_timer_pending = nested_vmx_preemption_timer_pending,
+ .has_events = vmx_has_nested_events,
.triple_fault = nested_vmx_triple_fault,
.get_state = vmx_get_nested_state,
.set_state = vmx_set_nested_state,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a6ab19afc638..0e73607b02bd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9471,8 +9471,8 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit)
}
if (is_guest_mode(vcpu) &&
- kvm_x86_ops.nested_ops->hv_timer_pending &&
- kvm_x86_ops.nested_ops->hv_timer_pending(vcpu))
+ kvm_x86_ops.nested_ops->has_events &&
+ kvm_x86_ops.nested_ops->has_events(vcpu))
*req_immediate_exit = true;
WARN_ON(vcpu->arch.exception.pending);
@@ -12183,8 +12183,8 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
return true;
if (is_guest_mode(vcpu) &&
- kvm_x86_ops.nested_ops->hv_timer_pending &&
- kvm_x86_ops.nested_ops->hv_timer_pending(vcpu))
+ kvm_x86_ops.nested_ops->has_events &&
+ kvm_x86_ops.nested_ops->has_events(vcpu))
return true;
return false;
--
2.31.1
On Wed, 2022-04-27 at 13:37 -0400, Paolo Bonzini wrote:
> Right now, the VMX preemption timer is special cased via the
> hv_timer_pending, but the purpose of the callback can be easily
> extended to observing any event that can occur only in non-root
> mode. Interrupts, NMIs etc. are already handled properly by
> the *_interrupt_allowed callbacks, so what is missing is only
> MTF. Check it in the newly-renamed callback, so that
> kvm_vcpu_running's call to kvm_check_nested_events
> becomes redundant.
>
> Cc: [email protected]
> Reported-by: Maxim Levitsky <[email protected]>
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---
> arch/x86/include/asm/kvm_host.h | 2 +-
> arch/x86/kvm/vmx/nested.c | 7 ++++++-
> arch/x86/kvm/x86.c | 8 ++++----
> 3 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 4ff36610af6a..e2e4f60159e9 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1504,7 +1504,7 @@ struct kvm_x86_ops {
> struct kvm_x86_nested_ops {
> void (*leave_nested)(struct kvm_vcpu *vcpu);
> int (*check_events)(struct kvm_vcpu *vcpu);
> - bool (*hv_timer_pending)(struct kvm_vcpu *vcpu);
> + bool (*has_events)(struct kvm_vcpu *vcpu);
> void (*triple_fault)(struct kvm_vcpu *vcpu);
> int (*get_state)(struct kvm_vcpu *vcpu,
> struct kvm_nested_state __user *user_kvm_nested_state,
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 856c87563883..54672025c3a1 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -3857,6 +3857,11 @@ static bool nested_vmx_preemption_timer_pending(struct kvm_vcpu *vcpu)
> to_vmx(vcpu)->nested.preemption_timer_expired;
> }
>
> +static bool vmx_has_nested_events(struct kvm_vcpu *vcpu)
> +{
Typo: needs struct vcpu_vmx *vmx = to_vmx(vcpu);
> + return nested_vmx_preemption_timer_pending(vcpu) || vmx->nested.mtf_pending;
> +}
> +
> static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
> {
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> @@ -6809,7 +6814,7 @@ __init int nested_vmx_hardware_setup(int (*exit_handlers[])(struct kvm_vcpu *))
> struct kvm_x86_nested_ops vmx_nested_ops = {
> .leave_nested = vmx_leave_nested,
> .check_events = vmx_check_nested_events,
> - .hv_timer_pending = nested_vmx_preemption_timer_pending,
> + .has_events = vmx_has_nested_events,
> .triple_fault = nested_vmx_triple_fault,
> .get_state = vmx_get_nested_state,
> .set_state = vmx_set_nested_state,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index a6ab19afc638..0e73607b02bd 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9471,8 +9471,8 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit)
> }
>
> if (is_guest_mode(vcpu) &&
> - kvm_x86_ops.nested_ops->hv_timer_pending &&
> - kvm_x86_ops.nested_ops->hv_timer_pending(vcpu))
> + kvm_x86_ops.nested_ops->has_events &&
> + kvm_x86_ops.nested_ops->has_events(vcpu))
> *req_immediate_exit = true;
>
> WARN_ON(vcpu->arch.exception.pending);
> @@ -12183,8 +12183,8 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
> return true;
>
> if (is_guest_mode(vcpu) &&
> - kvm_x86_ops.nested_ops->hv_timer_pending &&
> - kvm_x86_ops.nested_ops->hv_timer_pending(vcpu))
> + kvm_x86_ops.nested_ops->has_events &&
> + kvm_x86_ops.nested_ops->has_events(vcpu))
Nitpick: Won't it make sense to use conditional static call here instead?
> return true;
>
> return false;
Besides nitpicks,
Reviewed-by: Maxim Levitsky <[email protected]>
Wasn't able to test on my intel laptop, I am getting out of sudden in qemu:
'cpuid_data is full, no space for cpuid(eax:0x8000001d,ecx:0x3e)'
I will investigate tomorrow.
Best regards,
Maxim Levitsky
On Fri, Apr 29, 2022, Paolo Bonzini wrote:
> On 4/29/22 19:03, Sean Christopherson wrote:
> > This doesn't even compile...
> >
> > arch/x86/kvm/vmx/nested.c: In function ‘vmx_has_nested_events’:
> > arch/x86/kvm/vmx/nested.c:3862:61: error: ‘vmx’ undeclared (first use in this function)
> > 3862 | return nested_vmx_preemption_timer_pending(vcpu) || vmx->nested.mtf_pending;
> > | ^~~
> > arch/x86/kvm/vmx/nested.c:3862:61: note: each undeclared identifier is reported only once for each function it appears in
> > CC [M] arch/x86/kvm/svm/svm_onhyperv.o
> > arch/x86/kvm/vmx/nested.c:3863:1: error: control reaches end of non-void function [-Werror=return-type]
> > 3863 | }
> > | ^
> > cc1: all warnings being treated as errors
> > LD [M] arch/x86/kvm/kvm.o
>
> Yeah, it doesn't. Of course this will need a v2, also because there are
> failures in the vmx tests.
Heh, I suspected there would be failures, I was about to type up a response to
patch 3. MTF is subtly relying on the call from kvm_vcpu_running() to inject
the event.
From: Sean Christopherson <[email protected]>
Date: Fri, 29 Apr 2022 17:30:54 +0000
Subject: [PATCH] KVM: nVMX: Make an event request when pending an MTF nested
VM-Exit
Set KVM_REQ_EVENT when MTF becomes pending to ensure that KVM will run
through inject_pending_event() and thus vmx_check_nested_events() prior
to re-entering the guest. MTF currently works by virtue of KVM's hack
that calls kvm_check_nested_events() from kvm_vcpu_running(), but that
hack will be removed in the near future.
Fixes: 5ef8acbdd687 ("KVM: nVMX: Emulate MTF when performing instruction emulation")
Cc: [email protected]
Signed-off-by: Sean Christopherson <[email protected]>
---
arch/x86/kvm/vmx/vmx.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d58b763df855..4c635bc08105 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1577,10 +1577,12 @@ static void vmx_update_emulated_instruction(struct kvm_vcpu *vcpu)
*/
if (nested_cpu_has_mtf(vmcs12) &&
(!vcpu->arch.exception.pending ||
- vcpu->arch.exception.nr == DB_VECTOR))
+ vcpu->arch.exception.nr == DB_VECTOR)) {
vmx->nested.mtf_pending = true;
- else
+ kvm_make_request(KVM_REQ_EVENT, vcpu);
+ } else {
vmx->nested.mtf_pending = false;
+ }
}
static int vmx_skip_emulated_instruction(struct kvm_vcpu *vcpu)
base-commit: 39aa5903e8c407e5128c15aeabb0717b275b007e
--
On Wed, Apr 27, 2022, Paolo Bonzini wrote:
> Right now, the VMX preemption timer is special cased via the
> hv_timer_pending, but the purpose of the callback can be easily
> extended to observing any event that can occur only in non-root
> mode. Interrupts, NMIs etc. are already handled properly by
> the *_interrupt_allowed callbacks, so what is missing is only
> MTF. Check it in the newly-renamed callback, so that
> kvm_vcpu_running's call to kvm_check_nested_events
> becomes redundant.
>
> Cc: [email protected]
> Reported-by: Maxim Levitsky <[email protected]>
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---
> arch/x86/include/asm/kvm_host.h | 2 +-
> arch/x86/kvm/vmx/nested.c | 7 ++++++-
> arch/x86/kvm/x86.c | 8 ++++----
> 3 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 4ff36610af6a..e2e4f60159e9 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1504,7 +1504,7 @@ struct kvm_x86_ops {
> struct kvm_x86_nested_ops {
> void (*leave_nested)(struct kvm_vcpu *vcpu);
> int (*check_events)(struct kvm_vcpu *vcpu);
> - bool (*hv_timer_pending)(struct kvm_vcpu *vcpu);
> + bool (*has_events)(struct kvm_vcpu *vcpu);
> void (*triple_fault)(struct kvm_vcpu *vcpu);
> int (*get_state)(struct kvm_vcpu *vcpu,
> struct kvm_nested_state __user *user_kvm_nested_state,
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 856c87563883..54672025c3a1 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -3857,6 +3857,11 @@ static bool nested_vmx_preemption_timer_pending(struct kvm_vcpu *vcpu)
> to_vmx(vcpu)->nested.preemption_timer_expired;
> }
>
> +static bool vmx_has_nested_events(struct kvm_vcpu *vcpu)
> +{
> + return nested_vmx_preemption_timer_pending(vcpu) || vmx->nested.mtf_pending;
This doesn't even compile...
arch/x86/kvm/vmx/nested.c: In function ‘vmx_has_nested_events’:
arch/x86/kvm/vmx/nested.c:3862:61: error: ‘vmx’ undeclared (first use in this function)
3862 | return nested_vmx_preemption_timer_pending(vcpu) || vmx->nested.mtf_pending;
| ^~~
arch/x86/kvm/vmx/nested.c:3862:61: note: each undeclared identifier is reported only once for each function it appears in
CC [M] arch/x86/kvm/svm/svm_onhyperv.o
arch/x86/kvm/vmx/nested.c:3863:1: error: control reaches end of non-void function [-Werror=return-type]
3863 | }
| ^
cc1: all warnings being treated as errors
LD [M] arch/x86/kvm/kvm.o
On 4/29/22 19:03, Sean Christopherson wrote:
> This doesn't even compile...
>
> arch/x86/kvm/vmx/nested.c: In function ‘vmx_has_nested_events’:
> arch/x86/kvm/vmx/nested.c:3862:61: error: ‘vmx’ undeclared (first use in this function)
> 3862 | return nested_vmx_preemption_timer_pending(vcpu) || vmx->nested.mtf_pending;
> | ^~~
> arch/x86/kvm/vmx/nested.c:3862:61: note: each undeclared identifier is reported only once for each function it appears in
> CC [M] arch/x86/kvm/svm/svm_onhyperv.o
> arch/x86/kvm/vmx/nested.c:3863:1: error: control reaches end of non-void function [-Werror=return-type]
> 3863 | }
> | ^
> cc1: all warnings being treated as errors
> LD [M] arch/x86/kvm/kvm.o
Yeah, it doesn't. Of course this will need a v2, also because there are
failures in the vmx tests.
What can I say, testing these patches on AMD hardware wasn't a great idea.
Paolo
On 4/27/22 22:40, Maxim Levitsky wrote:
>
> Wasn't able to test on my intel laptop, I am getting out of sudden in qemu:
>
> 'cpuid_data is full, no space for cpuid(eax:0x8000001d,ecx:0x3e)'
Sending a patch soon, it's a QEMU bug that we have to work around.
Paolo