Live migration can happen when Arch LBR LBREn bit is cleared,
e.g., when migration happens after guest entered SMM mode.
In this case, we still need to migrate Arch LBR MSRs.

Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
 target/i386/kvm/kvm.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index a9ee8eebd7..e2d675115b 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -3373,15 +3373,14 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
             int i, ret;
 
             /*
-             * Only migrate Arch LBR states when: 1) Arch LBR is enabled
-             * for migrated vcpu. 2) the host Arch LBR depth equals that
-             * of source guest's, this is to avoid mismatch of guest/host
-             * config for the msr hence avoid unexpected misbehavior.
+             * Only migrate Arch LBR states when the host Arch LBR depth
+             * equals that of source guest's, this is to avoid mismatch
+             * of guest/host config for the msr hence avoid unexpected
+             * misbehavior.
              */
             ret = kvm_get_one_msr(cpu, MSR_ARCH_LBR_DEPTH, &depth);
 
-            if (ret == 1 && (env->msr_lbr_ctl & 0x1) && !!depth &&
-                depth == env->msr_lbr_depth) {
+            if (ret == 1 && !!depth && depth == env->msr_lbr_depth) {
                 kvm_msr_entry_add(cpu, MSR_ARCH_LBR_CTL, env->msr_lbr_ctl);
                 kvm_msr_entry_add(cpu, MSR_ARCH_LBR_DEPTH, env->msr_lbr_depth);
 
@@ -3801,13 +3800,11 @@ static int kvm_get_msrs(X86CPU *cpu)
 
     if (kvm_enabled() && cpu->enable_pmu &&
         (env->features[FEAT_7_0_EDX] & CPUID_7_0_EDX_ARCH_LBR)) {
-        uint64_t ctl, depth;
-        int i, ret2;
+        uint64_t depth;
+        int i, ret;
 
-        ret = kvm_get_one_msr(cpu, MSR_ARCH_LBR_CTL, &ctl);
-        ret2 = kvm_get_one_msr(cpu, MSR_ARCH_LBR_DEPTH, &depth);
-        if (ret == 1 && ret2 == 1 && (ctl & 0x1) &&
-            depth == ARCH_LBR_NR_ENTRIES) {
+        ret = kvm_get_one_msr(cpu, MSR_ARCH_LBR_DEPTH, &depth);
+        if (ret == 1 && depth == ARCH_LBR_NR_ENTRIES) {
             kvm_msr_entry_add(cpu, MSR_ARCH_LBR_CTL, 0);
             kvm_msr_entry_add(cpu, MSR_ARCH_LBR_DEPTH, 0);
 

base-commit: 8eccdb9eb84615291faef1257d5779ebfef7a0d0
-- 
2.27.0

On 5/17/22 17:50, Yang Weijiang wrote:
> Live migration can happen when Arch LBR LBREn bit is cleared,
> e.g., when migration happens after guest entered SMM mode.
> In this case, we still need to migrate Arch LBR MSRs.
> 
> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> ---
>   target/i386/kvm/kvm.c | 21 +++++++++------------
>   1 file changed, 9 insertions(+), 12 deletions(-)
> 
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index a9ee8eebd7..e2d675115b 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -3373,15 +3373,14 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
>               int i, ret;
>   
>               /*
> -             * Only migrate Arch LBR states when: 1) Arch LBR is enabled
> -             * for migrated vcpu. 2) the host Arch LBR depth equals that
> -             * of source guest's, this is to avoid mismatch of guest/host
> -             * config for the msr hence avoid unexpected misbehavior.
> +             * Only migrate Arch LBR states when the host Arch LBR depth
> +             * equals that of source guest's, this is to avoid mismatch
> +             * of guest/host config for the msr hence avoid unexpected
> +             * misbehavior.
>                */
>               ret = kvm_get_one_msr(cpu, MSR_ARCH_LBR_DEPTH, &depth);
>   
> -            if (ret == 1 && (env->msr_lbr_ctl & 0x1) && !!depth &&
> -                depth == env->msr_lbr_depth) {
> +            if (ret == 1 && !!depth && depth == env->msr_lbr_depth) {
>                   kvm_msr_entry_add(cpu, MSR_ARCH_LBR_CTL, env->msr_lbr_ctl);
>                   kvm_msr_entry_add(cpu, MSR_ARCH_LBR_DEPTH, env->msr_lbr_depth);
>   
> @@ -3801,13 +3800,11 @@ static int kvm_get_msrs(X86CPU *cpu)
>   
>       if (kvm_enabled() && cpu->enable_pmu &&
>           (env->features[FEAT_7_0_EDX] & CPUID_7_0_EDX_ARCH_LBR)) {
> -        uint64_t ctl, depth;
> -        int i, ret2;
> +        uint64_t depth;
> +        int i, ret;
>   
> -        ret = kvm_get_one_msr(cpu, MSR_ARCH_LBR_CTL, &ctl);
> -        ret2 = kvm_get_one_msr(cpu, MSR_ARCH_LBR_DEPTH, &depth);
> -        if (ret == 1 && ret2 == 1 && (ctl & 0x1) &&
> -            depth == ARCH_LBR_NR_ENTRIES) {
> +        ret = kvm_get_one_msr(cpu, MSR_ARCH_LBR_DEPTH, &depth);
> +        if (ret == 1 && depth == ARCH_LBR_NR_ENTRIES) {
>               kvm_msr_entry_add(cpu, MSR_ARCH_LBR_CTL, 0);
>               kvm_msr_entry_add(cpu, MSR_ARCH_LBR_DEPTH, 0);
>   
> 
> base-commit: 8eccdb9eb84615291faef1257d5779ebfef7a0d0

Queued, thanks.

Paolo