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

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index c400def..b649f92 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -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)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index e108fb4..d000cdd 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -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)

diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 8ddd381..521f74e 100644 (file)
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -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);                              \