Re: [PATCH v3 0/3] kvm: vmx: enable xsaves for kvm

Paolo Bonzini
2014-12-02T13:00:32Z

On 02/12/2014 12:14, Wanpeng Li wrote:
> This patchset is to enable xsaves for kvm part, the patch for
> qemu part will be sent out later.
>
> The patchset is tested on skylake-client.
>
> v2 -> v3:
> * add kvm_get/set for ia32_xss
> * fix the type XSS_EXIT_BITMAP
> * load host_xss just once in setup_vmcs_config
> * add/clear atuo switch ia32_xss msr in kvm_get/clear
> * add VMX_XSS_EXIT_BITMAP macro
> * add WARN() in handle_xsaves/xrstors
> * export xsaves if related vmcs field is set
>
> v1 -> v2:
> * auto switch ia32_xss msr just if this msr is present
>
> Wanpeng Li (3):
> kvm: x86: Intel XSAVES vmx and msr handle
> kvm: vmx: add kvm_get/set logic to xsaves
> kvm: x86: Enable Intel XSAVES for guest
>
> arch/x86/include/asm/kvm_host.h | 2 ++
> arch/x86/include/asm/vmx.h | 3 +++
> arch/x86/include/uapi/asm/vmx.h | 6 ++++-
> arch/x86/kvm/cpuid.c | 3 ++-
> arch/x86/kvm/vmx.c | 51 ++++++++++++++++++++++++++++++++++++++++-
> 5 files changed, 62 insertions(+), 3 deletions(-)
>

We need to return false from an svm_xsaves_supported function too, and
we need to prevent setting MSR_IA32_XSS to any non-zero value because
we do not support getting/setting a guest's Trace Packet Configuration
State.

I will squash this hunk in, and send a new patch to return zero for
CPUID(0xd,i).ECX and CPUID(0xd,i).EDX.

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 66d1e3d0195e..6e3a4486749c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2671,6 +2671,11 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_IA32_XSS:
if (!vmx_xsaves_supported())
return 1;
+ /* The only supported bit as of Skylake is bit 8, but
+ * it is not supported on KVM.
+ */
+ if (data != 0)
+ return 1;
vcpu->arch.ia32_xss = data;
if (vcpu->arch.ia32_xss != host_xss)
add_atomic_switch_msr(vmx, MSR_IA32_XSS,

Paolo