[Xen-changelog] [xen stable-4.6] x86/migrate: Move MSR_SPEC_CTRL on migrate

[patchbot@xxxxxxx]

commit db743b04998a9cbf6866b5f328855239a73220e5
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Wed Feb 14 13:40:10 2018 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Feb 14 13:40:10 2018 +0100

    x86/migrate: Move MSR_SPEC_CTRL on migrate
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: 0cf2a4eb769302b7d7d7835540e7b2f15006df30
    master date: 2018-01-26 14:10:21 +0000
---
 xen/arch/x86/domctl.c      | 31 +++++++++++++++++++++++++++++++
 xen/arch/x86/hvm/vmx/vmx.c | 25 ++++++++++++++++++++++++-
 2 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index 5aa0ed9..d964d81 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1045,6 +1045,8 @@ long arch_do_domctl(
                 vmsrs->msr_count = nr_msrs;
             else
             {
+                uint32_t edx, dummy;
+
                 i = 0;
 
                 vcpu_pause(v);
@@ -1082,6 +1084,21 @@ long arch_do_domctl(
                     }
                 }
 
+                domain_cpuid(d, 7, 0, &dummy, &dummy, &dummy, &edx);
+                if ( (edx & cpufeat_mask(X86_FEATURE_IBRSB)) &&
+                     v->arch.spec_ctrl )
+                {
+                    if ( i < vmsrs->msr_count && !ret )
+                    {
+                        msr.index = MSR_SPEC_CTRL;
+                        msr.reserved = 0;
+                        msr.value = v->arch.spec_ctrl;
+                        if ( copy_to_guest_offset(vmsrs->msrs, i, &msr, 1) )
+                            ret = -EFAULT;
+                    }
+                    ++i;
+                }
+
                 vcpu_unpause(v);
 
                 if ( i > vmsrs->msr_count && !ret )
@@ -1109,6 +1126,20 @@ long arch_do_domctl(
 
                 switch ( msr.index )
                 {
+                case MSR_SPEC_CTRL:
+                    if ( !boot_cpu_has(X86_FEATURE_IBRSB) )
+                        break; /* MSR available? */
+
+                    /*
+                     * Note: SPEC_CTRL_STIBP is specified as safe to use (i.e.
+                     * ignored) when STIBP isn't enumerated in hardware.
+                     */
+
+                    if ( msr.value & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP) )
+                        break;
+                    v->arch.spec_ctrl = msr.value;
+                    continue;
+
                 case MSR_AMD64_DR0_ADDRESS_MASK:
                     if ( !boot_cpu_has(X86_FEATURE_DBEXT) ||
                          (msr.value >> 32) )
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 5aac3f2..79fcfae 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -667,13 +667,23 @@ static bool_t vmx_set_guest_bndcfgs(struct vcpu *v, u64 
val)
 
 static unsigned int __init vmx_init_msr(void)
 {
-    return cpu_has_mpx && cpu_has_vmx_mpx;
+    return !!boot_cpu_has(X86_FEATURE_IBRSB) +
+           (cpu_has_mpx && cpu_has_vmx_mpx);
 }
 
 static void vmx_save_msr(struct vcpu *v, struct hvm_msr *ctxt)
 {
+    uint32_t edx, dummy;
+
     vmx_vmcs_enter(v);
 
+    domain_cpuid(v->domain, 7, 0, &dummy, &dummy, &dummy, &edx);
+    if ( (edx & cpufeat_mask(X86_FEATURE_IBRSB)) && v->arch.spec_ctrl )
+    {
+        ctxt->msr[ctxt->count].index = MSR_SPEC_CTRL;
+        ctxt->msr[ctxt->count++].val = v->arch.spec_ctrl;
+    }
+
     if ( cpu_has_mpx && cpu_has_vmx_mpx )
     {
         __vmread(GUEST_BNDCFGS, &ctxt->msr[ctxt->count].val);
@@ -695,6 +705,19 @@ static int vmx_load_msr(struct vcpu *v, struct hvm_msr 
*ctxt)
     {
         switch ( ctxt->msr[i].index )
         {
+        case MSR_SPEC_CTRL:
+            if ( !boot_cpu_has(X86_FEATURE_IBRSB) )
+                err = -ENXIO; /* MSR available? */
+            /*
+             * Note: SPEC_CTRL_STIBP is specified as safe to use (i.e.
+             * ignored) when STIBP isn't enumerated in hardware.
+             */
+            else if ( ctxt->msr[i].val &
+                      ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP) )
+                err = -ENXIO;
+            else
+                v->arch.spec_ctrl = ctxt->msr[i].val;
+            break;
         case MSR_IA32_BNDCFGS:
             if ( !vmx_set_guest_bndcfgs(v, ctxt->msr[i].val) &&
                  ctxt->msr[i].val )
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.6

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