From: Avi Kivity <avi@redhat.com>
To: Sheng Yang <sheng@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>, kvm@vger.kernel.org
Subject: Re: [PATCH 2/2] KVM: x86: XSAVE/XRSTOR live migration support
Date: Thu, 10 Jun 2010 12:19:25 +0300 [thread overview]
Message-ID: <4C10AE1D.40604@redhat.com> (raw)
In-Reply-To: <1276140433-29570-2-git-send-email-sheng@linux.intel.com>
On 06/10/2010 06:27 AM, Sheng Yang wrote:
> This patch enable save/restore of xsave state.
>
> Signed-off-by: Sheng Yang<sheng@linux.intel.com>
> ---
> Documentation/kvm/api.txt | 76 ++++++++++++++++++++++++++++++
> arch/x86/include/asm/kvm.h | 24 ++++++++++
> arch/x86/kvm/x86.c | 110 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/kvm.h | 12 +++++
> 4 files changed, 222 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt
> index 159b4ef..cb0afa2 100644
> --- a/Documentation/kvm/api.txt
> +++ b/Documentation/kvm/api.txt
> @@ -922,6 +922,82 @@ Define which vcpu is the Bootstrap Processor (BSP). Values are the same
> as the vcpu id in KVM_CREATE_VCPU. If this ioctl is not called, the default
> is vcpu 0.
>
> +4.41 KVM_GET_XSAVE
> +
> +Capability: KVM_CAP_XSAVE
> +Architectures: x86
> +Type: vcpu ioctl
> +Parameters: struct kvm_xsave (out)
> +Returns: 0 on success, -1 on error
> +
> +struct kvm_xsave {
> + __u32 size;
> + __u32 region[1000];
> +};
> +
> +This ioctl would copy current vcpu's xsave struct to the userspace.
>
How is size interpreted?
I think we can leave it out since it is implied by the xsave header.
>
> +/* for KVM_CAP_XSAVE */
> +struct kvm_xsave {
> + __u32 size;
> + __u32 reserved[3];
> + __u32 region[1020];
> +};
>
That's different from the documentation.
> +
> +#define KVM_MAX_XCRS 1
>
Needs to be much bigger for future compatibility, since it's part of the
ABI.
> @@ -2373,6 +2375,60 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu,
> return 0;
> }
>
> +static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
> + struct kvm_xsave *guest_xsave)
> +{
> + u32 size;
> +
> + if (cpu_has_xsave)
> + size = sizeof(struct xsave_struct);
> + else
> + size = sizeof(struct i387_fxsave_struct);
> +
> + guest_xsave->size = size;
> + memcpy(guest_xsave->region,&vcpu->arch.guest_fpu.state->xsave, size);
>
If !cpu_has_xsave, we can create a fake xsave header that says we have
the fpu and sse, so userspace doesn't have to look at size.
You're memcpy()ing state->xsave unconditionally, even if
!cpu_has_xsave. That works, but it's cleaner to access the ->fxsave member.
> +
> +static void kvm_vcpu_ioctl_x86_get_xcrs(struct kvm_vcpu *vcpu,
> + struct kvm_xcrs *guest_xcrs)
> +{
> + guest_xcrs->nr_xcrs = 1;
> + guest_xcrs->flags = 0;
> + guest_xcrs->xcrs[0].value = vcpu->arch.xcr0;
> +}
>
guest_xcrs[0].xcr = ...
What if !cpu_has_xsave? Probably should set nr_xcrs = 0.
> +
> +static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu *vcpu,
> + struct kvm_xcrs *guest_xcrs)
> +{
> + if (guest_xcrs->nr_xcrs< 1)
> + return 1;
>
Not really needed.
> +
> + /* Userspace may override the initial value of xcr0... */
> + if (guest_xcrs->xcrs[0].value != 0) {
>
Why check the value? What about checking the xcrs[].xcr?
> + vcpu->arch.xcr0 = guest_xcrs->xcrs[0].value;
> + vcpu->guest_xcr0_loaded = 0;
> + }
>
Need to loop over the array. Also, call kvm_set_xcr() to get checks to
be performed.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2010-06-10 9:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-10 3:27 [PATCH v8 1/2] KVM: VMX: Enable XSAVE/XRSTOR for guest Sheng Yang
2010-06-10 3:27 ` [PATCH 2/2] KVM: x86: XSAVE/XRSTOR live migration support Sheng Yang
2010-06-10 9:19 ` Avi Kivity [this message]
2010-06-10 9:05 ` [PATCH v8 1/2] KVM: VMX: Enable XSAVE/XRSTOR for guest Avi Kivity
2010-06-10 18:27 ` Marcelo Tosatti
2010-06-11 5:15 ` Avi Kivity
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