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From 39c3a18b4b956d0533e07de2640be064e07e3c97 Mon Sep 17 00:00:00 2001
From: Eduardo Habkost <ehabkost@redhat.com>
Date: Tue, 3 Dec 2019 23:53:08 +0000
Subject: [PATCH 2/2] target/i386: add support for MSR_IA32_TSX_CTRL

RH-Author: Eduardo Habkost <ehabkost@redhat.com>
Message-id: <20191203235308.590845-3-ehabkost@redhat.com>
Patchwork-id: 92850
O-Subject: [RHEL-8.2.0 qemu-kvm PATCH 2/2] target/i386: add support for MSR_IA32_TSX_CTRL
Bugzilla: 1771971
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
RH-Acked-by: Igor Mammedov <imammedo@redhat.com>

From: Paolo Bonzini <pbonzini@redhat.com>

The MSR_IA32_TSX_CTRL MSR can be used to hide TSX (also known as the
Trusty Side-channel Extension).  By virtualizing the MSR, KVM guests
can disable TSX and avoid paying the price of mitigating TSX-based
attacks on microarchitectural side channels.

Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 2a9758c51e2c2d13fc3845c3d603c11df98b8823)
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 target/i386/cpu.c     |  2 +-
 target/i386/cpu.h     |  4 ++++
 target/i386/kvm.c     | 13 +++++++++++++
 target/i386/machine.c | 20 ++++++++++++++++++++
 4 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 68fe865..ef6b958 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1143,7 +1143,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         .type = MSR_FEATURE_WORD,
         .feat_names = {
             "rdctl-no", "ibrs-all", "rsba", "skip-l1dfl-vmentry",
-            "ssb-no", "mds-no", NULL, NULL,
+            "ssb-no", "mds-no", NULL, "tsx-ctrl",
             "taa-no", NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 386e821..8d8814e 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -355,6 +355,9 @@ typedef enum X86Seg {
 #define MSR_IA32_PRED_CMD               0x49
 #define MSR_IA32_CORE_CAPABILITY        0xcf
 #define MSR_IA32_ARCH_CAPABILITIES      0x10a
+#define ARCH_CAP_TSX_CTRL_MSR		(1<<7)
+
+#define MSR_IA32_TSX_CTRL		0x122
 #define MSR_IA32_TSCDEADLINE            0x6e0
 
 #define FEATURE_CONTROL_LOCKED                    (1<<0)
@@ -1373,6 +1376,7 @@ typedef struct CPUX86State {
     uint64_t msr_smi_count;
 
     uint32_t pkru;
+    uint32_t tsx_ctrl;
 
     uint64_t spec_ctrl;
     uint64_t virt_ssbd;
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 6366172..107c53b 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -92,6 +92,7 @@ static bool has_msr_hv_stimer;
 static bool has_msr_hv_frequencies;
 static bool has_msr_xss;
 static bool has_msr_spec_ctrl;
+static bool has_msr_tsx_ctrl;
 static bool has_msr_virt_ssbd;
 static bool has_msr_smi_count;
 static bool has_msr_arch_capabs;
@@ -1458,6 +1459,9 @@ static int kvm_get_supported_msrs(KVMState *s)
             case MSR_IA32_SPEC_CTRL:
                 has_msr_spec_ctrl = true;
                 break;
+            case MSR_IA32_TSX_CTRL:
+                has_msr_tsx_ctrl = true;
+                break;
             case MSR_VIRT_SSBD:
                 has_msr_virt_ssbd = true;
                 break;
@@ -2095,6 +2099,9 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
     if (has_msr_spec_ctrl) {
         kvm_msr_entry_add(cpu, MSR_IA32_SPEC_CTRL, env->spec_ctrl);
     }
+    if (has_msr_tsx_ctrl) {
+        kvm_msr_entry_add(cpu, MSR_IA32_TSX_CTRL, env->tsx_ctrl);
+    }
     if (has_msr_virt_ssbd) {
         kvm_msr_entry_add(cpu, MSR_VIRT_SSBD, env->virt_ssbd);
     }
@@ -2491,6 +2498,9 @@ static int kvm_get_msrs(X86CPU *cpu)
     if (has_msr_spec_ctrl) {
         kvm_msr_entry_add(cpu, MSR_IA32_SPEC_CTRL, 0);
     }
+    if (has_msr_tsx_ctrl) {
+        kvm_msr_entry_add(cpu, MSR_IA32_TSX_CTRL, 0);
+    }
     if (has_msr_virt_ssbd) {
         kvm_msr_entry_add(cpu, MSR_VIRT_SSBD, 0);
     }
@@ -2862,6 +2872,9 @@ static int kvm_get_msrs(X86CPU *cpu)
         case MSR_IA32_SPEC_CTRL:
             env->spec_ctrl = msrs[i].data;
             break;
+        case MSR_IA32_TSX_CTRL:
+            env->tsx_ctrl = msrs[i].data;
+            break;
         case MSR_VIRT_SSBD:
             env->virt_ssbd = msrs[i].data;
             break;
diff --git a/target/i386/machine.c b/target/i386/machine.c
index fa8d1cc..76b173c 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -1226,6 +1226,25 @@ static const VMStateDescription vmstate_efer32 = {
 };
 #endif
 
+static bool msr_tsx_ctrl_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->features[FEAT_ARCH_CAPABILITIES] & ARCH_CAP_TSX_CTRL_MSR;
+}
+
+static const VMStateDescription vmstate_msr_tsx_ctrl = {
+    .name = "cpu/msr_tsx_ctrl",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = msr_tsx_ctrl_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(env.tsx_ctrl, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 VMStateDescription vmstate_x86_cpu = {
     .name = "cpu",
     .version_id = 12,
@@ -1357,6 +1376,7 @@ VMStateDescription vmstate_x86_cpu = {
 #ifdef CONFIG_KVM
         &vmstate_nested_state,
 #endif
+        &vmstate_msr_tsx_ctrl,
         NULL
     }
 };
-- 
1.8.3.1