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From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: jmattson@google.com,
	Sean Christopherson <sean.j.christopherson@intel.com>
Subject: [PATCH 5/5] KVM: vmx: use MSR_IA32_TSX_CTRL to hard-disable TSX on guest that lack it
Date: Mon, 18 Nov 2019 19:17:47 +0100	[thread overview]
Message-ID: <1574101067-5638-6-git-send-email-pbonzini@redhat.com> (raw)
In-Reply-To: <1574101067-5638-1-git-send-email-pbonzini@redhat.com>

If X86_FEATURE_RTM is disabled, the guest should not be able to access
MSR_IA32_TSX_CTRL.  We can therefore use it in KVM to force all
transactions from the guest to abort.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/vmx/vmx.c | 44 ++++++++++++++++++++++++++++++--------------
 1 file changed, 30 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index ed25fe7d5234..8cba65eec0d3 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -639,6 +639,23 @@ struct shared_msr_entry *find_msr_entry(struct vcpu_vmx *vmx, u32 msr)
 	return NULL;
 }
 
+static int vmx_set_guest_msr(struct vcpu_vmx *vmx, struct shared_msr_entry *msr, u64 data)
+{
+	int ret = 0;
+
+	u64 old_msr_data = msr->data;
+	msr->data = data;
+	if (msr - vmx->guest_msrs < vmx->save_nmsrs) {
+		preempt_disable();
+		ret = kvm_set_shared_msr(msr->index, msr->data,
+					 msr->mask);
+		preempt_enable();
+		if (ret)
+			msr->data = old_msr_data;
+	}
+	return ret;
+}
+
 void loaded_vmcs_init(struct loaded_vmcs *loaded_vmcs)
 {
 	vmcs_clear(loaded_vmcs->vmcs);
@@ -2174,20 +2191,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	default:
 	find_shared_msr:
 		msr = find_msr_entry(vmx, msr_index);
-		if (msr) {
-			u64 old_msr_data = msr->data;
-			msr->data = data;
-			if (msr - vmx->guest_msrs < vmx->save_nmsrs) {
-				preempt_disable();
-				ret = kvm_set_shared_msr(msr->index, msr->data,
-							 msr->mask);
-				preempt_enable();
-				if (ret)
-					msr->data = old_msr_data;
-			}
-			break;
-		}
-		ret = kvm_set_msr_common(vcpu, msr_info);
+		if (msr)
+			ret = vmx_set_guest_msr(vmx, msr, data);
+		else
+			ret = kvm_set_msr_common(vcpu, msr_info);
 	}
 
 	return ret;
@@ -7138,6 +7145,15 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 	if (boot_cpu_has(X86_FEATURE_INTEL_PT) &&
 			guest_cpuid_has(vcpu, X86_FEATURE_INTEL_PT))
 		update_intel_pt_cfg(vcpu);
+
+	if (boot_cpu_has(X86_FEATURE_RTM)) {
+		struct shared_msr_entry *msr;
+		msr = find_msr_entry(vmx, MSR_IA32_TSX_CTRL);
+		if (msr) {
+			bool enabled = guest_cpuid_has(vcpu, X86_FEATURE_RTM);
+			vmx_set_guest_msr(vmx, msr, enabled ? 0 : TSX_CTRL_RTM_DISABLE);
+		}
+	}
 }
 
 static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
-- 
1.8.3.1


  parent reply	other threads:[~2019-11-18 18:18 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-18 18:17 [PATCH 0/5] KVM: vmx: implement MSR_IA32_TSX_CTRL for guests Paolo Bonzini
2019-11-18 18:17 ` [PATCH 1/5] KVM: x86: fix presentation of TSX feature in ARCH_CAPABILITIES Paolo Bonzini
2019-11-18 19:39   ` Jim Mattson
2019-11-18 20:48   ` Jim Mattson
2019-11-22 20:15   ` Sean Christopherson
2019-11-18 18:17 ` [PATCH 2/5] KVM: x86: do not modify masked bits of shared MSRs Paolo Bonzini
2019-11-19 19:00   ` Jim Mattson
2019-11-18 18:17 ` [PATCH 3/5] KVM: x86: implement MSR_IA32_TSX_CTRL effect on CPUID Paolo Bonzini
2019-11-19 20:02   ` Jim Mattson
2019-11-18 18:17 ` [PATCH 4/5] KVM: vmx: implement MSR_IA32_TSX_CTRL disable RTM functionality Paolo Bonzini
2019-11-19 21:06   ` Jim Mattson
2019-11-20 12:21     ` Paolo Bonzini
2019-12-04 23:49   ` Jim Mattson
2019-12-05 10:16     ` Paolo Bonzini
2019-11-18 18:17 ` Paolo Bonzini [this message]
2019-11-21  2:22   ` [PATCH 5/5] KVM: vmx: use MSR_IA32_TSX_CTRL to hard-disable TSX on guest that lack it Eduardo Habkost
2019-11-21  9:05     ` Paolo Bonzini

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