From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Peter Zijlstra <peterz@infradead.org>,
Juergen Gross <jgross@suse.com>
Subject: [patch V2 5/7] x86/kvm/svm: Move guest enter/exit into .noinstr.text
Date: Wed, 08 Jul 2020 21:51:58 +0200 [thread overview]
Message-ID: <20200708195322.144607767@linutronix.de> (raw)
In-Reply-To: 20200708195153.746357686@linutronix.de
From: Thomas Gleixner <tglx@linutronix.de>
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>
---
arch/x86/kvm/svm/svm.c | 98 +++++++++++++++++++++++++--------------------
arch/x86/kvm/svm/vmenter.S | 2
2 files changed, 56 insertions(+), 44 deletions(-)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3344,6 +3344,60 @@ static fastpath_t svm_exit_handlers_fast
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;
@@ -3399,49 +3453,7 @@ static __no_kcsan fastpath_t svm_vcpu_ru
*/
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
--- 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
next prev parent reply other threads:[~2020-07-08 19:54 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-08 19:51 [patch V2 0/7] x86/kvm: RCU/context tracking and instrumentation protections Thomas Gleixner
2020-07-08 19:51 ` [patch V2 1/7] x86/kvm: Move context tracking where it belongs Thomas Gleixner
2020-07-08 19:51 ` [patch V2 2/7] x86/kvm/vmx: Add hardirq tracing to guest enter/exit Thomas Gleixner
2020-07-08 19:51 ` [patch V2 3/7] x86/kvm/svm: Add hardirq tracing on " Thomas Gleixner
2020-07-08 19:51 ` [patch V2 4/7] x86/kvm/vmx: Move guest enter/exit into .noinstr.text Thomas Gleixner
2020-07-08 19:51 ` Thomas Gleixner [this message]
2020-07-08 19:51 ` [patch V2 6/7] x86/kvm/svm: Use uninstrumented wrmsrl() to restore GS Thomas Gleixner
2020-07-08 19:52 ` [patch V2 7/7] x86/kvm/vmx: Use native read/write_cr2() Thomas Gleixner
2020-07-09 4:13 ` Jürgen Groß
2020-07-08 20:28 ` [patch V2 0/7] x86/kvm: RCU/context tracking and instrumentation protections Paolo Bonzini
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