Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=2345df8c555ecb92c0c36172c07d5ac321a92dc7 Commit: 2345df8c555ecb92c0c36172c07d5ac321a92dc7 Parent: c9047f533373e934b96d19d6a3d313ca2132fbe5 Author: Avi Kivity <[EMAIL PROTECTED]> AuthorDate: Tue Apr 17 15:30:24 2007 +0300 Committer: Avi Kivity <[EMAIL PROTECTED]> CommitDate: Thu May 3 10:52:29 2007 +0300
KVM: VMX: Reduce unnecessary saving of host msrs THe automatically switched msrs are never changed on the host (with the exception of MSR_KERNEL_GS_BASE) and thus there is no need to save them on every vm entry. This reduces vmexit latency by ~400 cycles on i386 and by ~900 cycles (10%) on x86_64. Signed-off-by: Avi Kivity <[EMAIL PROTECTED]> --- drivers/kvm/vmx.c | 12 +++++++++++- 1 files changed, 11 insertions(+), 1 deletions(-) diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c index 8c0115b..3745e6c 100644 --- a/drivers/kvm/vmx.c +++ b/drivers/kvm/vmx.c @@ -78,6 +78,10 @@ static const u32 vmx_msr_index[] = { }; #define NR_VMX_MSR ARRAY_SIZE(vmx_msr_index) +#ifdef CONFIG_X86_64 +static unsigned msr_offset_kernel_gs_base; +#endif + static inline int is_page_fault(u32 intr_info) { return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK | @@ -1129,6 +1133,10 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu) vcpu->host_msrs[j].reserved = 0; vcpu->host_msrs[j].data = data; vcpu->guest_msrs[j] = vcpu->host_msrs[j]; +#ifdef CONFIG_X86_64 + if (index == MSR_KERNEL_GS_BASE) + msr_offset_kernel_gs_base = j; +#endif ++vcpu->nmsrs; } @@ -1760,7 +1768,9 @@ again: fx_save(vcpu->host_fx_image); fx_restore(vcpu->guest_fx_image); - save_msrs(vcpu->host_msrs, vcpu->nmsrs); +#ifdef CONFIG_X86_64 + save_msrs(vcpu->host_msrs + msr_offset_kernel_gs_base, 1); +#endif load_msrs(vcpu->guest_msrs, NR_BAD_MSRS); asm ( - To unsubscribe from this list: send the line "unsubscribe git-commits-head" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html