On 09/05/2012 04:26 AM, Xudong Hao wrote:
> Enable KVM FPU fully eager restore, if there is other FPU state which isn't
> tracked by CR0.TS bit.
>
> Changes from v1:
> Expand KVM_XSTATE_LAZY to 64 bits before negating it.
>
> Signed-off-by: Xudong Hao <xudong.hao@xxxxxxxxx>
> ---
> arch/x86/include/asm/kvm.h | 4 ++++
> arch/x86/kvm/x86.c | 13 ++++++++++++-
> 2 files changed, 16 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
> index 521bf25..4c27056 100644
> --- a/arch/x86/include/asm/kvm.h
> +++ b/arch/x86/include/asm/kvm.h
> @@ -8,6 +8,8 @@
>
> #include <linux/types.h>
> #include <linux/ioctl.h>
> +#include <asm/user.h>
> +#include <asm/xsave.h>
>
> /* Select x86 specific features in <linux/kvm.h> */
> #define __KVM_HAVE_PIT
> @@ -30,6 +32,8 @@
> /* Architectural interrupt line count. */
> #define KVM_NR_INTERRUPTS 256
>
> +#define KVM_XSTATE_LAZY (XSTATE_FP | XSTATE_SSE | XSTATE_YMM)
> +
> struct kvm_memory_alias {
> __u32 slot; /* this has a different namespace than memory slots */
> __u32 flags;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 20f2266..a632042 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5969,7 +5969,18 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
> vcpu->guest_fpu_loaded = 0;
> fpu_save_init(&vcpu->arch.guest_fpu);
> ++vcpu->stat.fpu_reload;
> - kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
> + /*
> + * Currently KVM trigger FPU restore by #NM (via CR0.TS),
> + * till now only XCR0.bit0, XCR0.bit1, XCR0.bit2 is tracked
> + * by TS bit, there might be other FPU state is not tracked
> + * by TS bit. Here it only make FPU deactivate request and do
> + * FPU lazy restore for these cases: 1)xsave isn't enabled
> + * in guest, 2)all guest FPU states can be tracked by TS bit.
> + * For others, doing fully FPU eager restore.
> + */
> + if (!kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) ||
> + !(vcpu->arch.xcr0 & ~((u64)KVM_XSTATE_LAZY)))
> + kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
> trace_kvm_fpu(0);
> }
>
I think something is missing. This patch prevents
KVM_REQ_DEACTIVATE_FPU, but the fpu may not be active when non-lazy bits
are added to xcr0 (or cr4.osxsave is enabled). I think you need to
activate the fpu at that time as well.
--
error compiling committee.c: too many arguments to function
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