diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0033-KVM-VMX-Optimize-vmx_vcpu_run-and-svm_vcpu_run-by-ma.patch')
-rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0033-KVM-VMX-Optimize-vmx_vcpu_run-and-svm_vcpu_run-by-ma.patch | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0033-KVM-VMX-Optimize-vmx_vcpu_run-and-svm_vcpu_run-by-ma.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0033-KVM-VMX-Optimize-vmx_vcpu_run-and-svm_vcpu_run-by-ma.patch new file mode 100644 index 00000000..95086730 --- /dev/null +++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0033-KVM-VMX-Optimize-vmx_vcpu_run-and-svm_vcpu_run-by-ma.patch @@ -0,0 +1,65 @@ +From 885a241a441e144391884136534657f8502b2a48 Mon Sep 17 00:00:00 2001 +From: Paolo Bonzini <pbonzini@redhat.com> +Date: Thu, 22 Feb 2018 16:43:18 +0100 +Subject: [PATCH 33/33] KVM/VMX: Optimize vmx_vcpu_run() and svm_vcpu_run() by + marking the RDMSR path as unlikely() +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +commit 946fbbc13dce68902f64515b610eeb2a6c3d7a64 upstream. + +vmx_vcpu_run() and svm_vcpu_run() are large functions, and giving +branch hints to the compiler can actually make a substantial cycle +difference by keeping the fast path contiguous in memory. + +With this optimization, the retpoline-guest/retpoline-host case is +about 50 cycles faster. + +Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> +Reviewed-by: Jim Mattson <jmattson@google.com> +Cc: David Woodhouse <dwmw@amazon.co.uk> +Cc: KarimAllah Ahmed <karahmed@amazon.de> +Cc: Linus Torvalds <torvalds@linux-foundation.org> +Cc: Peter Zijlstra <peterz@infradead.org> +Cc: Radim Krčmář <rkrcmar@redhat.com> +Cc: Thomas Gleixner <tglx@linutronix.de> +Cc: kvm@vger.kernel.org +Cc: stable@vger.kernel.org +Link: http://lkml.kernel.org/r/20180222154318.20361-3-pbonzini@redhat.com +Signed-off-by: Ingo Molnar <mingo@kernel.org> +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + arch/x86/kvm/svm.c | 2 +- + arch/x86/kvm/vmx.c | 2 +- + 2 files changed, 2 insertions(+), 2 deletions(-) + +diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c +index 8d33396..b82bb66 100644 +--- a/arch/x86/kvm/svm.c ++++ b/arch/x86/kvm/svm.c +@@ -5017,7 +5017,7 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu) + * If the L02 MSR bitmap does not intercept the MSR, then we need to + * save it. + */ +- if (!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL)) ++ if (unlikely(!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL))) + svm->spec_ctrl = native_read_msr(MSR_IA32_SPEC_CTRL); + + if (svm->spec_ctrl) +diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c +index aa2684a..3c3558b 100644 +--- a/arch/x86/kvm/vmx.c ++++ b/arch/x86/kvm/vmx.c +@@ -9024,7 +9024,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu) + * If the L02 MSR bitmap does not intercept the MSR, then we need to + * save it. + */ +- if (!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL)) ++ if (unlikely(!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL))) + vmx->spec_ctrl = native_read_msr(MSR_IA32_SPEC_CTRL); + + if (vmx->spec_ctrl) +-- +2.7.4 + |