KVM Archive on lore.kernel.org
 help / color / Atom feed
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 v13 05/11] KVM: x86: Refresh CPUID once guest changes XSS bits
Date: Wed,  1 Jul 2020 16:04:05 +0800
Message-ID: <20200701080411.5802-6-weijiang.yang@intel.com> (raw)
In-Reply-To: <20200701080411.5802-1-weijiang.yang@intel.com>

CPUID(0xd, 1) reports the current required storage size of XCR0 | XSS,
when guest updates the XSS, it's necessary to update the CPUID leaf, otherwise
guest will fetch old state size, and results to some WARN traces during guest
running.

supported_xss is initialized to host_xss & KVM_SUPPORTED_XSS to indicate current
MSR_IA32_XSS bits supported in KVM, but actual XSS bits seen in guest depends
on the setting of CPUID(0xd,1).{ECX, EDX} for guest.

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            | 23 +++++++++++++++++++----
 arch/x86/kvm/x86.c              | 12 ++++++++----
 3 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 42a2d0d3984a..f68c825e94ad 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -649,6 +649,7 @@ struct kvm_vcpu_arch {
 
 	u64 xcr0;
 	u64 guest_supported_xcr0;
+	u64 guest_supported_xss;
 	u32 guest_xstate_size;
 
 	struct kvm_pio_request pio;
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 901cd1fdecd9..984ab2b395b3 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -89,15 +89,30 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
 		vcpu->arch.guest_xstate_size = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;
 	} else {
 		vcpu->arch.guest_supported_xcr0 =
-			(best->eax | ((u64)best->edx << 32)) & supported_xcr0;
+			(((u64)best->edx << 32) | best->eax) & supported_xcr0;
 		vcpu->arch.guest_xstate_size = 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;
+	}
 
 	/*
 	 * The existing code assumes virtual address is 48-bit or 57-bit in the
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b63727318da1..c866087ed0ef 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2843,9 +2843,12 @@ 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(vcpu);
+		}
 		break;
 	case MSR_SMI_COUNT:
 		if (!msr_info->host_initiated)
@@ -9678,8 +9681,9 @@ int kvm_arch_hardware_setup(void *opaque)
 
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 
-	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
-		supported_xss = 0;
+	supported_xss = 0;
+	if (kvm_cpu_cap_has(X86_FEATURE_XSAVES))
+		supported_xss = host_xss & KVM_SUPPORTED_XSS;
 
 	cr4_reserved_bits = kvm_host_cr4_reserved_bits(&boot_cpu_data);
 
-- 
2.17.2


  parent reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-01  8:04 [PATCH v13 00/11] Introduce support for guest CET feature Yang Weijiang
2020-07-01  8:04 ` [PATCH v13 01/11] KVM: x86: Include CET definitions for KVM test purpose Yang Weijiang
2020-07-01  8:04 ` [PATCH v13 02/11] KVM: VMX: Introduce CET VMCS fields and flags Yang Weijiang
2020-07-01  8:04 ` [PATCH v13 03/11] KVM: VMX: Set guest CET MSRs per KVM and host configuration Yang Weijiang
2020-07-02 15:13   ` Xiaoyao Li
2020-07-01  8:04 ` [PATCH v13 04/11] KVM: VMX: Configure CET settings upon guest CR0/4 changing Yang Weijiang
2020-07-01  8:04 ` Yang Weijiang [this message]
2020-07-01  8:04 ` [PATCH v13 06/11] KVM: x86: Load guest fpu state when access MSRs managed by XSAVES Yang Weijiang
2020-07-01  8:04 ` [PATCH v13 07/11] KVM: x86: Add userspace access interface for CET MSRs Yang Weijiang
2020-07-01  8:04 ` [PATCH v13 08/11] KVM: VMX: Enable CET support for nested VM Yang Weijiang
2020-07-01  8:04 ` [PATCH v13 09/11] KVM: VMX: Add VMCS dump and sanity check for CET states Yang Weijiang
2020-07-01  8:04 ` [PATCH v13 10/11] KVM: x86: Add #CP support in guest exception dispatch Yang Weijiang
2020-07-01  8:04 ` [PATCH v13 11/11] KVM: x86: Enable CET virtualization and advertise CET to userspace Yang Weijiang

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200701080411.5802-6-weijiang.yang@intel.com \
    --to=weijiang.yang@intel.com \
    --cc=jmattson@google.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pbonzini@redhat.com \
    --cc=sean.j.christopherson@intel.com \
    --cc=yu.c.zhang@linux.intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

KVM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvm/0 kvm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvm kvm/ https://lore.kernel.org/kvm \
		kvm@vger.kernel.org
	public-inbox-index kvm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.kvm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git