On 09/13/2012 07:29 PM, Marcelo Tosatti wrote:
> On Thu, Sep 13, 2012 at 01:26:36PM -0300, Marcelo Tosatti wrote:
>> On Wed, Sep 12, 2012 at 04:10:24PM +0800, Xudong Hao wrote:
>> > Enable KVM FPU fully eager restore, if there is other FPU state which isn't
>> > tracked by CR0.TS bit.
>> >
>> > v3 changes from v2:
>> > - Make fpu active explicitly while guest xsave is enabling and non-lazy xstate bit
>> > exist.
>>
>> How about a "guest_xcr0_can_lazy_saverestore" bool to control this?
>> It only needs to be updated when guest xcr0 is updated.
>>
>> That seems cleaner. Avi?
>
> Reasoning below.
>
>> > v2 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/vmx.c | 2 ++
>> > arch/x86/kvm/x86.c | 15 ++++++++++++++-
>> > 3 files changed, 20 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/vmx.c b/arch/x86/kvm/vmx.c
>> > index 248c2b4..853e875 100644
>> > --- a/arch/x86/kvm/vmx.c
>> > +++ b/arch/x86/kvm/vmx.c
>> > @@ -3028,6 +3028,8 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
>> >
>> > if (!vcpu->fpu_active)
>> > hw_cr0 |= X86_CR0_TS | X86_CR0_MP;
>> > + else
>> > + hw_cr0 &= ~(X86_CR0_TS | X86_CR0_MP);
>> >
>> > vmcs_writel(CR0_READ_SHADOW, cr0);
>> > vmcs_writel(GUEST_CR0, hw_cr0);
>> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> > index 20f2266..183cf60 100644
>> > --- a/arch/x86/kvm/x86.c
>> > +++ b/arch/x86/kvm/x86.c
>> > @@ -560,6 +560,8 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
>> > return 1;
>> > if (xcr0 & ~host_xcr0)
>> > return 1;
>> > + if (xcr0 & ~((u64)KVM_XSTATE_LAZY))
>> > + vcpu->fpu_active = 1;
>
> This is confusing. The variable allows to decrease the number of places
> the decision is made.
Better to have a helper function (lazy_fpu_allowed(), for example).
Variables raise the question of whether they are maintained correctly.
--
error compiling committee.c: too many arguments to function
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