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From: "Tian, Kevin" <kevin.tian@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>, "Christopherson,,
	Sean" <seanjc@google.com>, "Zhong, Yang" <yang.zhong@intel.com>
Cc: "x86@kernel.org" <x86@kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-kselftest@vger.kernel.org"
	<linux-kselftest@vger.kernel.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"bp@alien8.de" <bp@alien8.de>,
	"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
	"corbet@lwn.net" <corbet@lwn.net>,
	"shuah@kernel.org" <shuah@kernel.org>,
	"Nakajima, Jun" <jun.nakajima@intel.com>,
	"jing2.liu@linux.intel.com" <jing2.liu@linux.intel.com>,
	"Liu, Jing2" <jing2.liu@intel.com>,
	"Zeng, Guang" <guang.zeng@intel.com>,
	"Wang, Wei W" <wei.w.wang@intel.com>
Subject: RE: [PATCH v4 18/21] kvm: x86: Add support for getting/setting expanded xstate buffer
Date: Wed, 5 Jan 2022 04:03:33 +0000	[thread overview]
Message-ID: <BN9PR11MB5276A5116B76143CB694D1738C4B9@BN9PR11MB5276.namprd11.prod.outlook.com> (raw)
In-Reply-To: <c41a0458-1bfa-9dc6-71ce-f0433cd400e7@redhat.com>

> From: Paolo Bonzini <pbonzini@redhat.com>
> Sent: Wednesday, January 5, 2022 4:46 AM
> 
> On 1/4/22 20:46, Sean Christopherson wrote:
> > On Wed, Dec 29, 2021, Yang Zhong wrote:
> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> >> index bdf89c28d2ce..76e1941db223 100644
> >> --- a/arch/x86/kvm/x86.c
> >> +++ b/arch/x86/kvm/x86.c
> >> @@ -4296,6 +4296,11 @@ int kvm_vm_ioctl_check_extension(struct kvm
> *kvm, long ext)
> >>   		else
> >>   			r = 0;
> >>   		break;
> >> +	case KVM_CAP_XSAVE2:
> >> +		r = kvm->vcpus[0]->arch.guest_fpu.uabi_size;
> >
> > a) This does not compile against kvm/queue.
> >
> >     arch/x86/kvm/x86.c: In function ‘kvm_vm_ioctl_check_extension’:
> >     arch/x86/kvm/x86.c:4317:24: error: ‘struct kvm’ has no member named
> ‘vcpus’
> >      4317 |                 r = kvm->vcpus[0]->arch.guest_fpu.uabi_size;
> >
> > b) vcpu0 is not guaranteed to be non-NULL at this point.
> 
> Yang, you can post an incremental patch for this.  You can use the
> highest bit of the guest-permitted xcr0 (i.e. the OR of KVM's supported
> XCR0 an the guest-permitted dynamic features) and pass it to cpuid(0xD).
> 

Will do, except one correction that 'OR' should be 'AND' here. 😊

Thanks
Kevin

  reply	other threads:[~2022-01-05  4:03 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-29 13:13 [PATCH v4 00/21] AMX Support in KVM Yang Zhong
2021-12-29 13:13 ` [PATCH v4 01/21] x86/fpu: Extend fpu_xstate_prctl() with guest permissions Yang Zhong
2021-12-29 13:13 ` [PATCH v4 02/21] x86/fpu: Prepare guest FPU for dynamically enabled FPU features Yang Zhong
2021-12-29 13:13 ` [PATCH v4 03/21] kvm: x86: Fix xstate_required_size() to follow XSTATE alignment rule Yang Zhong
2022-01-04 19:54   ` Sean Christopherson
2021-12-29 13:13 ` [PATCH v4 04/21] kvm: x86: Exclude unpermitted xfeatures at KVM_GET_SUPPORTED_CPUID Yang Zhong
2021-12-29 13:13 ` [PATCH v4 05/21] x86/fpu: Make XFD initialization in __fpstate_reset() a function argument Yang Zhong
2021-12-29 13:13 ` [PATCH v4 06/21] x86/fpu: Add guest support to xfd_enable_feature() Yang Zhong
2021-12-29 13:13 ` [PATCH v4 07/21] x86/fpu: Provide fpu_update_guest_perm_features() for guest Yang Zhong
2021-12-29 13:13 ` [PATCH v4 08/21] kvm: x86: Check and enable permitted dynamic xfeatures at KVM_SET_CPUID2 Yang Zhong
2021-12-29 16:55   ` Sean Christopherson
2021-12-30  2:28     ` Tian, Kevin
2021-12-29 13:13 ` [PATCH v4 09/21] x86/fpu: Provide fpu_update_guest_xfd() for IA32_XFD emulation Yang Zhong
2021-12-29 13:13 ` [PATCH v4 10/21] kvm: x86: Add emulation for IA32_XFD Yang Zhong
2022-01-04 19:32   ` Sean Christopherson
2022-01-05  0:22     ` Tian, Kevin
2021-12-29 13:13 ` [PATCH v4 11/21] x86/fpu: Prepare xfd_err in struct fpu_guest Yang Zhong
2021-12-29 13:13 ` [PATCH v4 12/21] kvm: x86: Intercept #NM for saving IA32_XFD_ERR Yang Zhong
2022-01-04 20:01   ` Sean Christopherson
2022-01-05  0:27     ` Tian, Kevin
2021-12-29 13:13 ` [PATCH v4 13/21] kvm: x86: Emulate IA32_XFD_ERR for guest Yang Zhong
2021-12-29 13:13 ` [PATCH v4 14/21] kvm: x86: Disable RDMSR interception of IA32_XFD_ERR Yang Zhong
2022-01-04 19:34   ` Sean Christopherson
2022-01-05  0:23     ` Tian, Kevin
2021-12-29 13:13 ` [PATCH v4 15/21] kvm: x86: Add XCR0 support for Intel AMX Yang Zhong
2021-12-29 13:13 ` [PATCH v4 16/21] kvm: x86: Add CPUID " Yang Zhong
2021-12-29 13:13 ` [PATCH v4 17/21] x86/fpu: Add uabi_size to guest_fpu Yang Zhong
2021-12-29 13:13 ` [PATCH v4 18/21] kvm: x86: Add support for getting/setting expanded xstate buffer Yang Zhong
2022-01-04 19:46   ` Sean Christopherson
2022-01-04 20:45     ` Paolo Bonzini
2022-01-05  4:03       ` Tian, Kevin [this message]
2021-12-29 13:13 ` [PATCH v4 19/21] kvm: selftests: Add support for KVM_CAP_XSAVE2 Yang Zhong
2021-12-29 13:13 ` [PATCH v4 20/21] x86/fpu: Provide fpu_sync_guest_vmexit_xfd_state() Yang Zhong
2021-12-29 13:13 ` [PATCH v4 21/21] kvm: x86: Disable interception for IA32_XFD on demand Yang Zhong
2021-12-30  8:46 ` [PATCH v4 00/21] AMX Support in KVM Tian, Kevin
2022-01-04 18:36 ` Paolo Bonzini
2022-01-04 18:54   ` Sean Christopherson
2022-01-05  0:10     ` Tian, Kevin

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