x86/kvm/svm: Move guest enter/exit into .noinstr.text

Move the functions which are inside the RCU off region into the
non-instrumentable text section.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200708195322.144607767@linutronix.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 23bac92..71500e8 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3343,6 +3343,60 @@ static fastpath_t svm_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
 
 void __svm_vcpu_run(unsigned long vmcb_pa, unsigned long *regs);
 
+static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu,
+                                       struct vcpu_svm *svm)
+{
+       /*
+        * 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);
+
+       __svm_vcpu_run(svm->vmcb_pa, (unsigned long *)&svm->vcpu.arch.regs);
+
+#ifdef CONFIG_X86_64
+       wrmsrl(MSR_GS_BASE, svm->host.gs_base);
+#else
+       loadsegment(fs, svm->host.fs);
+#ifndef CONFIG_X86_32_LAZY_GS
+       loadsegment(gs, svm->host.gs);
+#endif
+#endif
+
+       /*
+        * 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().
+        *
+        * guest_exit_irqoff() 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);
+       guest_exit_irqoff();
+
+       instrumentation_begin();
+       trace_hardirqs_off_finish();
+       instrumentation_end();
+}
+
 static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
 {
        fastpath_t exit_fastpath;
@@ -3398,49 +3452,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
         */
        x86_spec_ctrl_set_guest(svm->spec_ctrl, svm->virt_spec_ctrl);
 
-       /*
-        * 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.
-        */
-       trace_hardirqs_on_prepare();
-       lockdep_hardirqs_on_prepare(CALLER_ADDR0);
-       guest_enter_irqoff();
-       lockdep_hardirqs_on(CALLER_ADDR0);
-
-       __svm_vcpu_run(svm->vmcb_pa, (unsigned long *)&svm->vcpu.arch.regs);
-
-#ifdef CONFIG_X86_64
-       wrmsrl(MSR_GS_BASE, svm->host.gs_base);
-#else
-       loadsegment(fs, svm->host.fs);
-#ifndef CONFIG_X86_32_LAZY_GS
-       loadsegment(gs, svm->host.gs);
-#endif
-#endif
-
-       /*
-        * 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().
-        *
-        * guest_exit_irqoff() 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);
-       guest_exit_irqoff();
-       trace_hardirqs_off_finish();
+       svm_vcpu_enter_exit(vcpu, svm);
 
        /*
         * We do not use IBRS in the kernel. If this vCPU has used the

diff --git a/arch/x86/kvm/svm/vmenter.S b/arch/x86/kvm/svm/vmenter.S
index bf94433..1ec1ac4 100644 (file)
--- a/arch/x86/kvm/svm/vmenter.S
+++ b/arch/x86/kvm/svm/vmenter.S
@@ -27,7 +27,7 @@
 #define VCPU_R15       __VCPU_REGS_R15 * WORD_SIZE
 #endif
 
-       .text
+.section .noinstr.text, "ax"
 
 /**
  * __svm_vcpu_run - Run a vCPU via a transition to SVM guest mode