On Mon, May 31, 2010 at 07:54:11PM +0800, Sheng Yang wrote:
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 99ae513..8649627 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -36,6 +36,8 @@
> #include <asm/vmx.h>
> #include <asm/virtext.h>
> #include <asm/mce.h>
> +#include <asm/i387.h>
> +#include <asm/xcr.h>
>
> #include "trace.h"
>
> @@ -3354,6 +3356,16 @@ static int handle_wbinvd(struct kvm_vcpu *vcpu)
> return 1;
> }
>
> +static int handle_xsetbv(struct kvm_vcpu *vcpu)
> +{
> + u64 new_bv = kvm_read_edx_eax(vcpu);
> + u32 index = kvm_register_read(vcpu, VCPU_REGS_RCX);
> +
> + kvm_set_xcr(vcpu, index, new_bv);
> + skip_emulated_instruction(vcpu);
Should only skip_emulated_instruction if no exception was injected.
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 7be1d36..0fcd8de 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> +int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
> +{
> + u64 xcr0;
> +
> + /* Only support XCR_XFEATURE_ENABLED_MASK(xcr0) now */
> + if (index != XCR_XFEATURE_ENABLED_MASK)
> + return 1;
> + xcr0 = xcr;
> + if (kvm_x86_ops->get_cpl(vcpu) != 0)
> + return 1;
> + if (!(xcr0 & XSTATE_FP))
> + return 1;
> + if ((xcr0 & XSTATE_YMM) && !(xcr0 & XSTATE_SSE))
> + return 1;
> + if (xcr0 & ~host_xcr0)
> + return 1;
> + vcpu->arch.xcr0 = xcr0;
> + xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0);
Won't this happen on guest entry, since vcpu->guest_xcr0_loaded == 0?
> @@ -4522,6 +4602,24 @@ static void inject_pending_event(struct kvm_vcpu *vcpu)
> }
> }
>
> +static void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu)
> +{
> + if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) &&
> + !vcpu->guest_xcr0_loaded) {
> + xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0);
Only necessary if guest and hosts XCR0 differ?
> + vcpu->guest_xcr0_loaded = 1;
> + }
> +}
> +
> +static void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu)
> +{
> + if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) &&
> + vcpu->guest_xcr0_loaded) {
> + xsetbv(XCR_XFEATURE_ENABLED_MASK, host_xcr0);
> + vcpu->guest_xcr0_loaded = 0;
> + }
> +}
What if you load guest's XCR0, then guest clears CR4.OSXSAVE? (restore
of host_xcr0 should be conditional on guest_xcr0_loaded only).
> +
> static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
> {
> int r;
> @@ -4567,6 +4665,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
> kvm_x86_ops->prepare_guest_switch(vcpu);
> if (vcpu->fpu_active)
> kvm_load_guest_fpu(vcpu);
> + kvm_load_guest_xcr0(vcpu);
>
> atomic_set(&vcpu->guest_mode, 1);
> smp_wmb();
> @@ -5118,6 +5217,11 @@ void fx_init(struct kvm_vcpu *vcpu)
> fpu_alloc(&vcpu->arch.guest_fpu);
> fpu_finit(&vcpu->arch.guest_fpu);
>
> + /*
> + * Ensure guest xcr0 is valid for loading
> + */
> + vcpu->arch.xcr0 = XSTATE_FP;
> +
> vcpu->arch.cr0 |= X86_CR0_ET;
> }
> EXPORT_SYMBOL_GPL(fx_init);
> @@ -5132,6 +5236,12 @@ void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
> if (vcpu->guest_fpu_loaded)
> return;
>
> + /*
> + * Restore all possible states in the guest,
> + * and assume host would use all available bits.
> + * Guest xcr0 would be loaded later.
> + */
> + kvm_put_guest_xcr0(vcpu);
> vcpu->guest_fpu_loaded = 1;
> unlazy_fpu(current);
> fpu_restore_checking(&vcpu->arch.guest_fpu);
> @@ -5140,6 +5250,8 @@ void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
>
> void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
> {
> + kvm_put_guest_xcr0(vcpu);
> +
Should be in kvm_arch_vcpu_put?
> if (!vcpu->guest_fpu_loaded)
> return;
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 4e8fdbf..3784d58 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -88,7 +88,7 @@ struct kvm_vcpu {
> int srcu_idx;
>
> int fpu_active;
> - int guest_fpu_loaded;
> + int guest_fpu_loaded, guest_xcr0_loaded;
> wait_queue_head_t wq;
> int sigset_active;
> sigset_t sigset;
> --
> 1.7.0.1
>
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