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KVM: x86: Consolidate guest enter/exit logic to common helpers 

Move the enter/exit logic in {svm,vmx}_vcpu_enter_exit() to common
helpers.  Opportunistically update the somewhat stale comment about the
updates needing to occur immediately after VM-Exit.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210505002735.1684165-9-seanjc@google.com
This commit is contained in:
Sean Christopherson 2021-05-04 17:27:35 -07:00 committed by Thomas Gleixner
parent 1ca0016c14
commit bc908e091b
3 changed files with 49 additions and 74 deletions
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39
arch/x86/kvm/svm/svm.c
View File

@ -3710,25 +3710,7 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
struct vcpu_svm *svm = to_svm(vcpu);
unsigned long vmcb_pa = svm->current_vmcb->pa;
/*
* VMENTER enables interrupts (host state), but the kernel state is
* interrupts disabled when this is invoked. Also tell RCU about
* it. This is the same logic as for exit_to_user_mode().
*
* This ensures that e.g. latency analysis on the host observes
* guest mode as interrupt enabled.
*
* guest_enter_irqoff() informs context tracking about the
* transition to guest mode and if enabled adjusts RCU state
* accordingly.
*/
instrumentation_begin();
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare(CALLER_ADDR0);
instrumentation_end();
guest_enter_irqoff();
lockdep_hardirqs_on(CALLER_ADDR0);
kvm_guest_enter_irqoff();
if (sev_es_guest(vcpu->kvm)) {
__svm_sev_es_vcpu_run(vmcb_pa);
@ -3748,24 +3730,7 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
vmload(__sme_page_pa(sd->save_area));
}
/*
* VMEXIT disables interrupts (host state), but tracing and lockdep
* have them in state 'on' as recorded before entering guest mode.
* Same as enter_from_user_mode().
*
* context_tracking_guest_exit() restores host context and reinstates
* RCU if enabled and required.
*
* This needs to be done before the below as native_read_msr()
* contains a tracepoint and x86_spec_ctrl_restore_host() calls
* into world and some more.
*/
lockdep_hardirqs_off(CALLER_ADDR0);
context_tracking_guest_exit();
instrumentation_begin();
trace_hardirqs_off_finish();
instrumentation_end();
kvm_guest_exit_irqoff();
}
static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)

39
arch/x86/kvm/vmx/vmx.c
View File

@ -6664,25 +6664,7 @@ static fastpath_t vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
struct vcpu_vmx *vmx)
{
/*
* VMENTER enables interrupts (host state), but the kernel state is
* interrupts disabled when this is invoked. Also tell RCU about
* it. This is the same logic as for exit_to_user_mode().
*
* This ensures that e.g. latency analysis on the host observes
* guest mode as interrupt enabled.
*
* guest_enter_irqoff() informs context tracking about the
* transition to guest mode and if enabled adjusts RCU state
* accordingly.
*/
instrumentation_begin();
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare(CALLER_ADDR0);
instrumentation_end();
guest_enter_irqoff();
lockdep_hardirqs_on(CALLER_ADDR0);
kvm_guest_enter_irqoff();
/* L1D Flush includes CPU buffer clear to mitigate MDS */
if (static_branch_unlikely(&vmx_l1d_should_flush))
@ -6698,24 +6680,7 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
vcpu->arch.cr2 = native_read_cr2();
/*
* VMEXIT disables interrupts (host state), but tracing and lockdep
* have them in state 'on' as recorded before entering guest mode.
* Same as enter_from_user_mode().
*
* context_tracking_guest_exit() restores host context and reinstates
* RCU if enabled and required.
*
* This needs to be done before the below as native_read_msr()
* contains a tracepoint and x86_spec_ctrl_restore_host() calls
* into world and some more.
*/
lockdep_hardirqs_off(CALLER_ADDR0);
context_tracking_guest_exit();
instrumentation_begin();
trace_hardirqs_off_finish();
instrumentation_end();
kvm_guest_exit_irqoff();
}
static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)

45
arch/x86/kvm/x86.h
View File

@ -8,6 +8,51 @@
#include "kvm_cache_regs.h"
#include "kvm_emulate.h"
static __always_inline void kvm_guest_enter_irqoff(void)
{
/*
* VMENTER enables interrupts (host state), but the kernel state is
* interrupts disabled when this is invoked. Also tell RCU about
* it. This is the same logic as for exit_to_user_mode().
*
* This ensures that e.g. latency analysis on the host observes
* guest mode as interrupt enabled.
*
* guest_enter_irqoff() informs context tracking about the
* transition to guest mode and if enabled adjusts RCU state
* accordingly.
*/
instrumentation_begin();
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare(CALLER_ADDR0);
instrumentation_end();
guest_enter_irqoff();
lockdep_hardirqs_on(CALLER_ADDR0);
}
static __always_inline void kvm_guest_exit_irqoff(void)
{
/*
* VMEXIT disables interrupts (host state), but tracing and lockdep
* have them in state 'on' as recorded before entering guest mode.
* Same as enter_from_user_mode().
*
* context_tracking_guest_exit() restores host context and reinstates
* RCU if enabled and required.
*
* This needs to be done immediately after VM-Exit, before any code
* that might contain tracepoints or call out to the greater world,
* e.g. before x86_spec_ctrl_restore_host().
*/
lockdep_hardirqs_off(CALLER_ADDR0);
context_tracking_guest_exit();
instrumentation_begin();
trace_hardirqs_off_finish();
instrumentation_end();
}
#define KVM_NESTED_VMENTER_CONSISTENCY_CHECK(consistency_check) \
({ \
bool failed = (consistency_check); \