lkml.org 
[lkml]   [2020]   [Jul]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[patch V2 5/7] x86/kvm/svm: Move guest enter/exit into .noinstr.text
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
\
 
 \ /
  Last update: 2020-07-08 21:54    [W:0.041 / U:9.532 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site