From 70913a1bded444b1d264c3723fca2f6a7966d667 Mon Sep 17 00:00:00 2001

From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Date: Mon, 21 May 2018 22:54:24 +0100

Subject: [PATCH 2/3] i386: Define the Virt SSBD MSR and handling of it

 (CVE-2018-3639)

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"Some AMD processors only support a non-architectural means of enabling

speculative store bypass disable (SSBD).  To allow a simplified view of

this to a guest, an architectural definition has been created through a new

CPUID bit, 0x80000008_EBX[25], and a new MSR, 0xc001011f.  With this, a

hypervisor can virtualize the existence of this definition and provide an

architectural method for using SSBD to a guest.

Add the new CPUID feature, the new MSR and update the existing SSBD

support to use this MSR when present." (from x86/speculation: Add virtualized

speculative store bypass disable support in Linux).

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Message-Id: <20180521215424.13520-4-berrange@redhat.com>

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

(cherry picked from commit cfeea0c021db6234c154dbc723730e81553924ff)

---

 target/i386/cpu.h     |  2 ++

 target/i386/kvm.c     | 16 ++++++++++++++--

 target/i386/machine.c | 20 ++++++++++++++++++++

 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h

index 970ab96e54..75e821cefe 100644

--- a/target/i386/cpu.h

+++ b/target/i386/cpu.h

@@ -351,6 +351,7 @@ typedef enum X86Seg {

 #define MSR_IA32_FEATURE_CONTROL        0x0000003a

 #define MSR_TSC_ADJUST                  0x0000003b

 #define MSR_IA32_SPEC_CTRL              0x48

+#define MSR_VIRT_SSBD                   0xc001011f

 #define MSR_IA32_TSCDEADLINE            0x6e0

 #define FEATURE_CONTROL_LOCKED                    (1<<0)

@@ -1150,6 +1151,7 @@ typedef struct CPUX86State {

     uint32_t pkru;

     uint64_t spec_ctrl;

+    uint64_t virt_ssbd;

     /* End of state preserved by INIT (dummy marker).  */

     struct {} end_init_save;

diff --git a/target/i386/kvm.c b/target/i386/kvm.c

index 6c49954e68..19e6aa320d 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_virt_ssbd;

 static bool has_msr_smi_count;

 static uint32_t has_architectural_pmu_version;

@@ -1218,6 +1219,9 @@ static int kvm_get_supported_msrs(KVMState *s)

                 case MSR_IA32_SPEC_CTRL:

                     has_msr_spec_ctrl = true;

                     break;

+                case MSR_VIRT_SSBD:

+                    has_msr_virt_ssbd = true;

+                    break;

                 }

             }

         }

@@ -1706,6 +1710,10 @@ 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_virt_ssbd) {

+        kvm_msr_entry_add(cpu, MSR_VIRT_SSBD, env->virt_ssbd);

+    }

+

 #ifdef TARGET_X86_64

     if (lm_capable_kernel) {

         kvm_msr_entry_add(cpu, MSR_CSTAR, env->cstar);

@@ -2077,8 +2085,9 @@ 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_virt_ssbd) {

+        kvm_msr_entry_add(cpu, MSR_VIRT_SSBD, 0);

+    }

     if (!env->tsc_valid) {

         kvm_msr_entry_add(cpu, MSR_IA32_TSC, 0);

         env->tsc_valid = !runstate_is_running();

@@ -2444,6 +2453,9 @@ static int kvm_get_msrs(X86CPU *cpu)

         case MSR_IA32_SPEC_CTRL:

             env->spec_ctrl = msrs[i].data;

             break;

+        case MSR_VIRT_SSBD:

+            env->virt_ssbd = msrs[i].data;

+            break;

         case MSR_IA32_RTIT_CTL:

             env->msr_rtit_ctrl = msrs[i].data;

             break;

diff --git a/target/i386/machine.c b/target/i386/machine.c

index bd2d82e91b..f0a835c292 100644

--- a/target/i386/machine.c

+++ b/target/i386/machine.c

@@ -893,6 +893,25 @@ static const VMStateDescription vmstate_msr_intel_pt = {

     }

 };

+static bool virt_ssbd_needed(void *opaque)

+{

+    X86CPU *cpu = opaque;

+    CPUX86State *env = &cpu->env;

+

+    return env->virt_ssbd != 0;

+}

+

+static const VMStateDescription vmstate_msr_virt_ssbd = {

+    .name = "cpu/virt_ssbd",

+    .version_id = 1,

+    .minimum_version_id = 1,

+    .needed = virt_ssbd_needed,

+    .fields = (VMStateField[]){

+        VMSTATE_UINT64(env.virt_ssbd, X86CPU),

+        VMSTATE_END_OF_LIST()

+    }

+};

+

 VMStateDescription vmstate_x86_cpu = {

     .name = "cpu",

     .version_id = 12,

@@ -1015,6 +1034,7 @@ VMStateDescription vmstate_x86_cpu = {

         &vmstate_spec_ctrl,

         &vmstate_mcg_ext_ctl,

         &vmstate_msr_intel_pt,

+        &vmstate_msr_virt_ssbd,

         NULL

     }

 };

-- 

2.17.0