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From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Xiaoyao Li <xiaoyao.li@intel.com>,
	Reiji Watanabe <reijiw@google.com>
Subject: [PATCH 11/15] KVM: VMX: Disable loading of TSX_CTRL MSR the more conventional way
Date: Tue,  4 May 2021 10:17:30 -0700	[thread overview]
Message-ID: <20210504171734.1434054-12-seanjc@google.com> (raw)
In-Reply-To: <20210504171734.1434054-1-seanjc@google.com>

Tag TSX_CTRL as not needing to be loaded when RTM isn't supported in the
host.  Crushing the write mask to '0' has the same effect, but requires
more mental gymnastics to understand.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/vmx/vmx.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4b432d2bbd06..7a53568b34fc 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1771,7 +1771,13 @@ static void setup_msrs(struct vcpu_vmx *vmx)
 			   guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDTSCP) ||
 			   guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDPID));
 
-	vmx_setup_uret_msr(vmx, MSR_IA32_TSX_CTRL, true);
+	/*
+	 * hle=0, rtm=0, tsx_ctrl=1 can be found with some combinations of new
+	 * kernel and old userspace.  If those guests run on a tsx=off host, do
+	 * allow guests to use TSX_CTRL, but don't change the value in hardware
+	 * so that TSX remains always disabled.
+	 */
+	vmx_setup_uret_msr(vmx, MSR_IA32_TSX_CTRL, boot_cpu_has(X86_FEATURE_RTM));
 
 	if (cpu_has_vmx_msr_bitmap())
 		vmx_update_msr_bitmap(&vmx->vcpu);
@@ -6919,23 +6925,15 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
 		vmx->guest_uret_msrs[i].data = 0;
 		vmx->guest_uret_msrs[i].mask = -1ull;
 	}
-	tsx_ctrl = vmx_find_uret_msr(vmx, MSR_IA32_TSX_CTRL);
-	if (tsx_ctrl) {
+	if (boot_cpu_has(X86_FEATURE_RTM)) {
 		/*
 		 * TSX_CTRL_CPUID_CLEAR is handled in the CPUID interception.
 		 * Keep the host value unchanged to avoid changing CPUID bits
 		 * under the host kernel's feet.
-		 *
-		 * hle=0, rtm=0, tsx_ctrl=1 can be found with some combinations
-		 * of new kernel and old userspace.  If those guests run on a
-		 * tsx=off host, do allow guests to use TSX_CTRL, but do not
-		 * change the value on the host so that TSX remains always
-		 * disabled.
 		 */
-		if (boot_cpu_has(X86_FEATURE_RTM))
+		tsx_ctrl = vmx_find_uret_msr(vmx, MSR_IA32_TSX_CTRL);
+		if (tsx_ctrl)
 			vmx->guest_uret_msrs[i].mask = ~(u64)TSX_CTRL_CPUID_CLEAR;
-		else
-			vmx->guest_uret_msrs[i].mask = 0;
 	}
 
 	err = alloc_loaded_vmcs(&vmx->vmcs01);
-- 
2.31.1.527.g47e6f16901-goog


  parent reply	other threads:[~2021-05-04 17:18 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-04 17:17 [PATCH 00/15] KVM: x86: RDPID/RDTSCP fixes and uret MSR cleanups Sean Christopherson
2021-05-04 17:17 ` [PATCH 01/15] KVM: VMX: Do not adverise RDPID if ENABLE_RDTSCP control is unsupported Sean Christopherson
2021-05-04 17:37   ` Jim Mattson
2021-05-04 17:53     ` Jim Mattson
2021-05-04 18:14       ` Sean Christopherson
2021-05-05  3:04   ` Reiji Watanabe
2021-05-10  8:03   ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 02/15] KVM: x86: Emulate RDPID only if RDTSCP is supported Sean Christopherson
2021-05-04 17:50   ` Jim Mattson
2021-05-05  3:51   ` Reiji Watanabe
2021-05-05  8:01     ` Paolo Bonzini
2021-05-10  8:08   ` Maxim Levitsky
2021-05-10 17:20     ` Sean Christopherson
2021-05-11 12:32       ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 03/15] KVM: SVM: Inject #UD on RDTSCP when it should be disabled in the guest Sean Christopherson
2021-05-04 21:45   ` Jim Mattson
2021-05-04 21:53     ` Sean Christopherson
2021-05-04 21:56       ` Jim Mattson
2021-05-04 22:10         ` Sean Christopherson
2021-05-04 22:24           ` Jim Mattson
2021-05-04 21:57       ` Paolo Bonzini
2021-05-04 21:58         ` Jim Mattson
2021-05-10  8:08           ` Maxim Levitsky
2021-05-10 16:56             ` Sean Christopherson
2021-05-11 12:34               ` Maxim Levitsky
2021-05-18 10:59               ` Paolo Bonzini
2021-05-18 19:24                 ` Sean Christopherson
2021-05-05  4:26   ` Reiji Watanabe
2021-05-10  8:08   ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 04/15] KVM: x86: Move RDPID emulation intercept to its own enum Sean Christopherson
2021-05-04 23:24   ` Jim Mattson
2021-05-10  8:14   ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 05/15] KVM: VMX: Disable preemption when probing user return MSRs Sean Christopherson
2021-05-04 23:36   ` Jim Mattson
2021-05-10  8:18   ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 06/15] KVM: SVM: Probe and load MSR_TSC_AUX regardless of RDTSCP support in host Sean Christopherson
2021-05-10  8:20   ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 07/15] KVM: x86: Add support for RDPID without RDTSCP Sean Christopherson
2021-05-10  8:20   ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 08/15] KVM: VMX: Configure list of user return MSRs at module init Sean Christopherson
2021-05-10  8:23   ` Maxim Levitsky
2021-05-10 15:13     ` Sean Christopherson
2021-05-11 12:34       ` Maxim Levitsky
2021-05-11 20:10         ` Sean Christopherson
2021-05-04 17:17 ` [PATCH 09/15] KVM: VMX: Use flag to indicate "active" uret MSRs instead of sorting list Sean Christopherson
2021-05-08  3:31   ` Reiji Watanabe
2021-05-10 16:43     ` Sean Christopherson
2021-05-10 17:55       ` Reiji Watanabe
2021-05-10  8:25   ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 10/15] KVM: VMX: Use common x86's uret MSR list as the one true list Sean Christopherson
2021-05-10  8:25   ` Maxim Levitsky
2021-05-04 17:17 ` Sean Christopherson [this message]
2021-05-05  8:49   ` [PATCH 11/15] KVM: VMX: Disable loading of TSX_CTRL MSR the more conventional way Paolo Bonzini
2021-05-05 15:36     ` Sean Christopherson
2021-05-05 15:50       ` Paolo Bonzini
2021-05-10  8:26   ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 12/15] KVM: x86: Export the number of uret MSRs to vendor modules Sean Christopherson
2021-05-10  8:27   ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 13/15] KVM: x86: Move uret MSR slot management to common x86 Sean Christopherson
2021-05-10  8:28   ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 14/15] KVM: x86: Tie Intel and AMD behavior for MSR_TSC_AUX to guest CPU model Sean Christopherson
2021-05-10  8:29   ` Maxim Levitsky
2021-05-10 16:50     ` Sean Christopherson
2021-05-10 17:11       ` Jim Mattson
2021-05-11 12:34         ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 15/15] KVM: x86: Hide RDTSCP and RDPID if MSR_TSC_AUX probing failed Sean Christopherson
2021-05-10  8:29   ` Maxim Levitsky
2021-05-05  8:51 ` [PATCH 00/15] KVM: x86: RDPID/RDTSCP fixes and uret MSR cleanups Paolo Bonzini

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