linux-kernel - [PATCH v3] KVM: x86: Sync the states size with the XCR0/IA32

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <dc8c75a6-a39f-be1d-6cf3-024b88bdf5fe@gmail.com>
Date:   Sun, 23 Jan 2022 12:37:44 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH v3] KVM: x86: Sync the states size with the XCR0/IA32_XSS at,
 any time

From: Like Xu <likexu@...cent.com>

XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by
both RESET and INIT. The kvm_set_msr_common()'s handling of MSR_IA32_XSS
also needs to update kvm_update_cpuid_runtime(). In the above cases, the
size in bytes of the XSAVE area containing all states enabled by XCR0 or
(XCRO | IA32_XSS) needs to be updated.

For simplicity and consistency, existing helpers are used to write values
and call kvm_update_cpuid_runtime(), and it's not exactly a fast path.

Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
Signed-off-by: Like Xu <likexu@...cent.com>
---
v2 -> v3 Changelog:
- Apply s/legacy/existing in the commit message; (Sean)
- Invoke kvm_update_cpuid_runtime() for MSR_IA32_XSS; (Sean)

  arch/x86/kvm/x86.c | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 55518b7d3b96..4b509b26d9ab 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3535,6 +3535,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct 
msr_data *msr_info)
  		if (data & ~supported_xss)
  			return 1;
  		vcpu->arch.ia32_xss = data;
+		kvm_update_cpuid_runtime(vcpu);
  		break;
  	case MSR_SMI_COUNT:
  		if (!msr_info->host_initiated)
@@ -11256,7 +11257,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)

  		vcpu->arch.msr_misc_features_enables = 0;

-		vcpu->arch.xcr0 = XFEATURE_MASK_FP;
+		__kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP);
  	}

  	/* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */
@@ -11273,7 +11274,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
  	cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
  	kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);

-	vcpu->arch.ia32_xss = 0;
+	__kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true);

  	static_call(kvm_x86_vcpu_reset)(vcpu, init_event);

-- 
2.33.1