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From: Yang Weijiang <weijiang.yang@intel.com>
To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	pbonzini@redhat.com, sean.j.christopherson@intel.com,
	jmattson@google.com
Cc: yu.c.zhang@linux.intel.com, Yang Weijiang <weijiang.yang@intel.com>
Subject: [PATCH v14 02/13] KVM: x86: Refresh CPUID on writes to MSR_IA32_XSS
Date: Fri,  6 Nov 2020 09:16:26 +0800	[thread overview]
Message-ID: <20201106011637.14289-3-weijiang.yang@intel.com> (raw)
In-Reply-To: <20201106011637.14289-1-weijiang.yang@intel.com>

Updated CPUID.0xD.0x1, which reports the current required storage size
of all features enabled via XCR0 | XSS, when the guest's XSS is modified.

Note, KVM does not yet support any XSS based features, i.e. supported_xss
is guaranteed to be zero at this time.

Co-developed-by: Zhang Yi Z <yi.z.zhang@linux.intel.com>
Signed-off-by: Zhang Yi Z <yi.z.zhang@linux.intel.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/cpuid.c            | 21 ++++++++++++++++++---
 arch/x86/kvm/x86.c              |  7 +++++--
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index d44858b69353..1620a2cca781 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -611,6 +611,7 @@ struct kvm_vcpu_arch {
 
 	u64 xcr0;
 	u64 guest_supported_xcr0;
+	u64 guest_supported_xss;
 
 	struct kvm_pio_request pio;
 	void *pio_data;
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 06a278b3701d..2c737337f466 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -115,9 +115,24 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
 		best->ebx = xstate_required_size(vcpu->arch.xcr0, false);
 
 	best = kvm_find_cpuid_entry(vcpu, 0xD, 1);
-	if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||
-		     cpuid_entry_has(best, X86_FEATURE_XSAVEC)))
-		best->ebx = xstate_required_size(vcpu->arch.xcr0, true);
+	if (best) {
+		if (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||
+		    cpuid_entry_has(best, X86_FEATURE_XSAVEC))  {
+			u64 xstate = vcpu->arch.xcr0 | vcpu->arch.ia32_xss;
+
+			best->ebx = xstate_required_size(xstate, true);
+		}
+
+		if (!cpuid_entry_has(best, X86_FEATURE_XSAVES)) {
+			best->ecx = 0;
+			best->edx = 0;
+		}
+		vcpu->arch.guest_supported_xss =
+			(((u64)best->edx << 32) | best->ecx) & supported_xss;
+
+	} else {
+		vcpu->arch.guest_supported_xss = 0;
+	}
 
 	best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0);
 	if (kvm_hlt_in_guest(vcpu->kvm) && best &&
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fce18a2537ea..0823bf1e2977 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3124,9 +3124,12 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		 * IA32_XSS[bit 8]. Guests have to use RDMSR/WRMSR rather than
 		 * XSAVES/XRSTORS to save/restore PT MSRs.
 		 */
-		if (data & ~supported_xss)
+		if (data & ~vcpu->arch.guest_supported_xss)
 			return 1;
-		vcpu->arch.ia32_xss = data;
+		if (vcpu->arch.ia32_xss != data) {
+			vcpu->arch.ia32_xss = data;
+			kvm_update_cpuid_runtime(vcpu);
+		}
 		break;
 	case MSR_SMI_COUNT:
 		if (!msr_info->host_initiated)
-- 
2.17.2


  parent reply	other threads:[~2020-11-06  1:06 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-06  1:16 [PATCH v14 00/13] Introduce support for guest CET feature Yang Weijiang
2020-11-06  1:16 ` [PATCH v14 01/13] KVM: x86: Report XSS as an MSR to be saved if there are supported features Yang Weijiang
2020-11-06  1:16 ` Yang Weijiang [this message]
2020-11-06  1:16 ` [PATCH v14 03/13] KVM: x86: Add #CP support in guest exception dispatch Yang Weijiang
2020-11-06  1:16 ` [PATCH v14 04/13] KVM: VMX: Introduce CET VMCS fields and flags Yang Weijiang
2020-11-06  1:16 ` [PATCH v14 05/13] KVM: x86: Add fault checks for CR4.CET Yang Weijiang
2020-11-09 10:44   ` kernel test robot
2020-11-09 10:44     ` kernel test robot
2020-11-06  1:16 ` [PATCH v14 06/13] KVM: x86: Load guest fpu state when accessing MSRs managed by XSAVES Yang Weijiang
2020-11-06  1:16 ` [PATCH v14 07/13] KVM: VMX: Emulate reads and writes to CET MSRs Yang Weijiang
2021-01-28 17:45   ` Paolo Bonzini
2021-01-29  8:07     ` Yang Weijiang
2020-11-06  1:16 ` [PATCH v14 08/13] KVM: VMX: Add a synthetic MSR to allow userspace VMM to access GUEST_SSP Yang Weijiang
2021-01-28 17:41   ` Paolo Bonzini
2021-01-28 17:42   ` Paolo Bonzini
2020-11-06  1:16 ` [PATCH v14 09/13] KVM: x86: Report CET MSRs as to-be-saved if CET is supported Yang Weijiang
2020-11-09  6:17   ` kernel test robot
2020-11-09  6:17     ` kernel test robot
2021-01-28 17:46   ` Paolo Bonzini
2021-01-29  8:08     ` Yang Weijiang
2020-11-06  1:16 ` [PATCH v14 10/13] KVM: x86: Enable CET virtualization for VMX and advertise CET to userspace Yang Weijiang
2020-11-09  7:23   ` kernel test robot
2020-11-09  7:23     ` kernel test robot
2021-01-28 17:53   ` Paolo Bonzini
     [not found]     ` <20210129112437.GA29715@local-michael-cet-test.sh.intel.com>
     [not found]       ` <68e288ee-6e09-36f1-a6c9-bed864eb7678@redhat.com>
     [not found]         ` <20210129121717.GA30243@local-michael-cet-test.sh.intel.com>
     [not found]           ` <1cf7e501-2c69-8b76-9332-42db1348ab08@redhat.com>
2021-01-30  6:32             ` Yang Weijiang
2021-02-01  4:56             ` Yang Weijiang
2020-11-06  1:16 ` [PATCH v14 11/13] KVM: VMX: Pass through CET MSRs to the guest when supported Yang Weijiang
2021-01-28 17:54   ` Paolo Bonzini
2021-01-28 18:04     ` Paolo Bonzini
2020-11-06  1:16 ` [PATCH v14 12/13] KVM: nVMX: Add helper to check the vmcs01 MSR bitmap for MSR pass-through Yang Weijiang
2020-11-06  1:16 ` [PATCH v14 13/13] KVM: nVMX: Enable CET support for nested VMX Yang Weijiang
2021-01-28 17:57 ` [PATCH v14 00/13] Introduce support for guest CET feature Paolo Bonzini
2021-01-28 18:04   ` Sean Christopherson
2021-01-28 18:06     ` Paolo Bonzini
2021-01-28 18:24       ` Sean Christopherson

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