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[Qemu-devel] [PATCH v5 3/3] x86: define a new MSR based feature word -- FEATURE_WORDS_ARCH_CAPABILITIES

Robert Hoo posted 3 patches 7 years ago
There is a newer version of this series
[Qemu-devel] [PATCH v5 3/3] x86: define a new MSR based feature word -- FEATURE_WORDS_ARCH_CAPABILITIES
Posted by Robert Hoo 7 years ago 
Note RSBA is specially treated -- no matter host support it or not, qemu
pretends it is supported.

Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
---
 target/i386/cpu.c | 31 ++++++++++++++++++++++++++++++-
 target/i386/cpu.h |  8 ++++++++
 target/i386/kvm.c | 11 +++++++++++
 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index d191b9c..51c8fd8 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1141,6 +1141,27 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         },
         .tcg_features = ~0U,
     },
+    /*Below are MSR exposed features*/
+    [FEAT_ARCH_CAPABILITIES] = {
+        .type = MSR_FEATURE_WORD,
+        .feat_names = {
+            "rdctl-no", "ibrs-all", "rsba", "skip-l1dfl-vmentry",
+            "ssb-no", NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+        },
+        .msr = {
+            .index = MSR_IA32_ARCH_CAPABILITIES,
+            .cpuid_dep = {
+                FEAT_7_0_EDX,
+                CPUID_7_0_EDX_ARCH_CAPABILITIES
+            }
+        },
+    },
 };
 
 typedef struct X86RegisterInfo32 {
@@ -3696,7 +3717,15 @@ static uint32_t x86_cpu_get_supported_feature_word(FeatureWord w,
                                                         wi->cpuid.reg);
             break;
         case MSR_FEATURE_WORD:
-            r = kvm_arch_get_supported_msr_feature(kvm_state, wi->msr.index);
+            /* Special case:
+             * No matter host status, IA32_ARCH_CAPABILITIES.RSBA [bit 2]
+             * is always supported in guest.
+             */
+            if (wi->msr.index == MSR_IA32_ARCH_CAPABILITIES) {
+                r = MSR_ARCH_CAP_RSBA;
+            }
+            r |= kvm_arch_get_supported_msr_feature(kvm_state,
+                        wi->msr.index);
             break;
         }
     } else if (hvf_enabled()) {
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 730c06f..52a52ec 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -502,6 +502,7 @@ typedef enum FeatureWord {
     FEAT_6_EAX,         /* CPUID[6].EAX */
     FEAT_XSAVE_COMP_LO, /* CPUID[EAX=0xd,ECX=0].EAX */
     FEAT_XSAVE_COMP_HI, /* CPUID[EAX=0xd,ECX=0].EDX */
+    FEAT_ARCH_CAPABILITIES,
     FEATURE_WORDS,
 } FeatureWord;
 
@@ -730,6 +731,13 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
 #define CPUID_TOPOLOGY_LEVEL_SMT      (1U << 8)
 #define CPUID_TOPOLOGY_LEVEL_CORE     (2U << 8)
 
+/* MSR Feature Bits */
+#define MSR_ARCH_CAP_RDCL_NO    (1U << 0)
+#define MSR_ARCH_CAP_IBRS_ALL   (1U << 1)
+#define MSR_ARCH_CAP_RSBA       (1U << 2)
+#define MSR_ARCH_CAP_SKIP_L1DFL_VMENTRY (1U << 3)
+#define MSR_ARCH_CAP_SSB_NO     (1U << 4)
+
 #ifndef HYPERV_SPINLOCK_NEVER_RETRY
 #define HYPERV_SPINLOCK_NEVER_RETRY             0xFFFFFFFF
 #endif
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index db79dad..2f7b40d 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -1928,6 +1928,17 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
     }
 #endif
 
+    /* If host supports feature MSR, write down. */
+    if (kvm_feature_msrs) {
+        int i;
+        for (i = 0; i < kvm_feature_msrs->nmsrs; i++)
+            if (kvm_feature_msrs->indices[i] == MSR_IA32_ARCH_CAPABILITIES) {
+                kvm_msr_entry_add(cpu, MSR_IA32_ARCH_CAPABILITIES,
+                              env->features[FEAT_ARCH_CAPABILITIES]);
+                break;
+            }
+    }
+
     /*
      * The following MSRs have side effects on the guest or are too heavy
      * for normal writeback. Limit them to reset or full state updates.
-- 
1.8.3.1
Re: [Qemu-devel] [PATCH v5 3/3] x86: define a new MSR based feature word -- FEATURE_WORDS_ARCH_CAPABILITIES
Posted by Eduardo Habkost 7 years ago 
On Mon, Oct 15, 2018 at 12:47:25PM +0800, Robert Hoo wrote:
> Note RSBA is specially treated -- no matter host support it or not, qemu
> pretends it is supported.
> 
> Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>

I am now wondering what else we need to be able to remove
CPUID_7_0_EDX_ARCH_CAPABILITIES from
feature_word_info[FEAT_7_0_EDX].unmigratable_flags.

This series is necessary for that, be I think we still can't let
the VM be migrated if arch-capabilities is enabled and we're
running on a host that doesn't have MSR_IA32_ARCH_CAPABILITIES on
kvm_feature_msrs.

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

> ---
>  target/i386/cpu.c | 31 ++++++++++++++++++++++++++++++-
>  target/i386/cpu.h |  8 ++++++++
>  target/i386/kvm.c | 11 +++++++++++
>  3 files changed, 49 insertions(+), 1 deletion(-)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index d191b9c..51c8fd8 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -1141,6 +1141,27 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
>          },
>          .tcg_features = ~0U,
>      },
> +    /*Below are MSR exposed features*/
> +    [FEAT_ARCH_CAPABILITIES] = {
> +        .type = MSR_FEATURE_WORD,
> +        .feat_names = {
> +            "rdctl-no", "ibrs-all", "rsba", "skip-l1dfl-vmentry",
> +            "ssb-no", NULL, NULL, NULL,
> +            NULL, NULL, NULL, NULL,
> +            NULL, NULL, NULL, NULL,
> +            NULL, NULL, NULL, NULL,
> +            NULL, NULL, NULL, NULL,
> +            NULL, NULL, NULL, NULL,
> +            NULL, NULL, NULL, NULL,
> +        },
> +        .msr = {
> +            .index = MSR_IA32_ARCH_CAPABILITIES,
> +            .cpuid_dep = {
> +                FEAT_7_0_EDX,
> +                CPUID_7_0_EDX_ARCH_CAPABILITIES
> +            }
> +        },
> +    },
>  };
>  
>  typedef struct X86RegisterInfo32 {
> @@ -3696,7 +3717,15 @@ static uint32_t x86_cpu_get_supported_feature_word(FeatureWord w,
>                                                          wi->cpuid.reg);
>              break;
>          case MSR_FEATURE_WORD:
> -            r = kvm_arch_get_supported_msr_feature(kvm_state, wi->msr.index);
> +            /* Special case:
> +             * No matter host status, IA32_ARCH_CAPABILITIES.RSBA [bit 2]
> +             * is always supported in guest.
> +             */
> +            if (wi->msr.index == MSR_IA32_ARCH_CAPABILITIES) {
> +                r = MSR_ARCH_CAP_RSBA;
> +            }
> +            r |= kvm_arch_get_supported_msr_feature(kvm_state,
> +                        wi->msr.index);
>              break;
>          }
>      } else if (hvf_enabled()) {
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 730c06f..52a52ec 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -502,6 +502,7 @@ typedef enum FeatureWord {
>      FEAT_6_EAX,         /* CPUID[6].EAX */
>      FEAT_XSAVE_COMP_LO, /* CPUID[EAX=0xd,ECX=0].EAX */
>      FEAT_XSAVE_COMP_HI, /* CPUID[EAX=0xd,ECX=0].EDX */
> +    FEAT_ARCH_CAPABILITIES,
>      FEATURE_WORDS,
>  } FeatureWord;
>  
> @@ -730,6 +731,13 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
>  #define CPUID_TOPOLOGY_LEVEL_SMT      (1U << 8)
>  #define CPUID_TOPOLOGY_LEVEL_CORE     (2U << 8)
>  
> +/* MSR Feature Bits */
> +#define MSR_ARCH_CAP_RDCL_NO    (1U << 0)
> +#define MSR_ARCH_CAP_IBRS_ALL   (1U << 1)
> +#define MSR_ARCH_CAP_RSBA       (1U << 2)
> +#define MSR_ARCH_CAP_SKIP_L1DFL_VMENTRY (1U << 3)
> +#define MSR_ARCH_CAP_SSB_NO     (1U << 4)
> +
>  #ifndef HYPERV_SPINLOCK_NEVER_RETRY
>  #define HYPERV_SPINLOCK_NEVER_RETRY             0xFFFFFFFF
>  #endif
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index db79dad..2f7b40d 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -1928,6 +1928,17 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
>      }
>  #endif
>  
> +    /* If host supports feature MSR, write down. */
> +    if (kvm_feature_msrs) {
> +        int i;
> +        for (i = 0; i < kvm_feature_msrs->nmsrs; i++)
> +            if (kvm_feature_msrs->indices[i] == MSR_IA32_ARCH_CAPABILITIES) {
> +                kvm_msr_entry_add(cpu, MSR_IA32_ARCH_CAPABILITIES,
> +                              env->features[FEAT_ARCH_CAPABILITIES]);
> +                break;
> +            }
> +    }
> +
>      /*
>       * The following MSRs have side effects on the guest or are too heavy
>       * for normal writeback. Limit them to reset or full state updates.
> -- 
> 1.8.3.1
> 
> 

-- 
Eduardo
Re: [Qemu-devel] [PATCH v5 3/3] x86: define a new MSR based feature word -- FEATURE_WORDS_ARCH_CAPABILITIES
Posted by Robert Hoo 7 years ago 
On Wed, 2018-10-24 at 07:06 -0300, Eduardo Habkost wrote:
> On Mon, Oct 15, 2018 at 12:47:25PM +0800, Robert Hoo wrote:
> > Note RSBA is specially treated -- no matter host support it or not,
> > qemu
> > pretends it is supported.
> > 
> > Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
> 
> I am now wondering what else we need to be able to remove
> CPUID_7_0_EDX_ARCH_CAPABILITIES from
> feature_word_info[FEAT_7_0_EDX].unmigratable_flags.

Let me know once some thought comes out to you.
> 
> This series is necessary for that, be I think we still can't let
> the VM be migrated if arch-capabilities is enabled and we're
> running on a host that doesn't have MSR_IA32_ARCH_CAPABILITIES on
> kvm_feature_msrs.

Agree. So I still keep CPUID_7_0_EDX_ARCH_CAPABILITIES in
feature_word_info[FEAT_7_0_EDX].unmigratable_flags for now.
> 
> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
> 
> > ---
> >  target/i386/cpu.c | 31 ++++++++++++++++++++++++++++++-
> >  target/i386/cpu.h |  8 ++++++++
> >  target/i386/kvm.c | 11 +++++++++++
> >  3 files changed, 49 insertions(+), 1 deletion(-)
> > 
> > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > index d191b9c..51c8fd8 100644
> > --- a/target/i386/cpu.c
> > +++ b/target/i386/cpu.c
> > @@ -1141,6 +1141,27 @@ static FeatureWordInfo
> > feature_word_info[FEATURE_WORDS] = {
> >          },
> >          .tcg_features = ~0U,
> >      },
> > +    /*Below are MSR exposed features*/
> > +    [FEAT_ARCH_CAPABILITIES] = {
> > +        .type = MSR_FEATURE_WORD,
> > +        .feat_names = {
> > +            "rdctl-no", "ibrs-all", "rsba", "skip-l1dfl-vmentry",
> > +            "ssb-no", NULL, NULL, NULL,
> > +            NULL, NULL, NULL, NULL,
> > +            NULL, NULL, NULL, NULL,
> > +            NULL, NULL, NULL, NULL,
> > +            NULL, NULL, NULL, NULL,
> > +            NULL, NULL, NULL, NULL,
> > +            NULL, NULL, NULL, NULL,
> > +        },
> > +        .msr = {
> > +            .index = MSR_IA32_ARCH_CAPABILITIES,
> > +            .cpuid_dep = {
> > +                FEAT_7_0_EDX,
> > +                CPUID_7_0_EDX_ARCH_CAPABILITIES
> > +            }
> > +        },
> > +    },
> >  };
> >  
> >  typedef struct X86RegisterInfo32 {
> > @@ -3696,7 +3717,15 @@ static uint32_t
> > x86_cpu_get_supported_feature_word(FeatureWord w,
> >                                                          wi-
> > >cpuid.reg);
> >              break;
> >          case MSR_FEATURE_WORD:
> > -            r = kvm_arch_get_supported_msr_feature(kvm_state, wi-
> > >msr.index);
> > +            /* Special case:
> > +             * No matter host status, IA32_ARCH_CAPABILITIES.RSBA
> > [bit 2]
> > +             * is always supported in guest.
> > +             */
> > +            if (wi->msr.index == MSR_IA32_ARCH_CAPABILITIES) {
> > +                r = MSR_ARCH_CAP_RSBA;
> > +            }
> > +            r |= kvm_arch_get_supported_msr_feature(kvm_state,
> > +                        wi->msr.index);
> >              break;
> >          }
> >      } else if (hvf_enabled()) {
> > diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> > index 730c06f..52a52ec 100644
> > --- a/target/i386/cpu.h
> > +++ b/target/i386/cpu.h
> > @@ -502,6 +502,7 @@ typedef enum FeatureWord {
> >      FEAT_6_EAX,         /* CPUID[6].EAX */
> >      FEAT_XSAVE_COMP_LO, /* CPUID[EAX=0xd,ECX=0].EAX */
> >      FEAT_XSAVE_COMP_HI, /* CPUID[EAX=0xd,ECX=0].EDX */
> > +    FEAT_ARCH_CAPABILITIES,
> >      FEATURE_WORDS,
> >  } FeatureWord;
> >  
> > @@ -730,6 +731,13 @@ typedef uint32_t
> > FeatureWordArray[FEATURE_WORDS];
> >  #define CPUID_TOPOLOGY_LEVEL_SMT      (1U << 8)
> >  #define CPUID_TOPOLOGY_LEVEL_CORE     (2U << 8)
> >  
> > +/* MSR Feature Bits */
> > +#define MSR_ARCH_CAP_RDCL_NO    (1U << 0)
> > +#define MSR_ARCH_CAP_IBRS_ALL   (1U << 1)
> > +#define MSR_ARCH_CAP_RSBA       (1U << 2)
> > +#define MSR_ARCH_CAP_SKIP_L1DFL_VMENTRY (1U << 3)
> > +#define MSR_ARCH_CAP_SSB_NO     (1U << 4)
> > +
> >  #ifndef HYPERV_SPINLOCK_NEVER_RETRY
> >  #define HYPERV_SPINLOCK_NEVER_RETRY             0xFFFFFFFF
> >  #endif
> > diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> > index db79dad..2f7b40d 100644
> > --- a/target/i386/kvm.c
> > +++ b/target/i386/kvm.c
> > @@ -1928,6 +1928,17 @@ static int kvm_put_msrs(X86CPU *cpu, int
> > level)
> >      }
> >  #endif
> >  
> > +    /* If host supports feature MSR, write down. */
> > +    if (kvm_feature_msrs) {
> > +        int i;
> > +        for (i = 0; i < kvm_feature_msrs->nmsrs; i++)
> > +            if (kvm_feature_msrs->indices[i] ==
> > MSR_IA32_ARCH_CAPABILITIES) {
> > +                kvm_msr_entry_add(cpu, MSR_IA32_ARCH_CAPABILITIES,
> > +                              env-
> > >features[FEAT_ARCH_CAPABILITIES]);
> > +                break;
> > +            }
> > +    }
> > +
> >      /*
> >       * The following MSRs have side effects on the guest or are
> > too heavy
> >       * for normal writeback. Limit them to reset or full state
> > updates.
> > -- 
> > 1.8.3.1
> > 
> > 
> 
>
Re: [Qemu-devel] [PATCH v5 3/3] x86: define a new MSR based feature word -- FEATURE_WORDS_ARCH_CAPABILITIES
Posted by Robert Hoo 7 years ago 
On Wed, 2018-10-24 at 07:06 -0300, Eduardo Habkost wrote:
> On Mon, Oct 15, 2018 at 12:47:25PM +0800, Robert Hoo wrote:
> > Note RSBA is specially treated -- no matter host support it or not,
> > qemu
> > pretends it is supported.
> > 
> > Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
> 
> I am now wondering what else we need to be able to remove
> CPUID_7_0_EDX_ARCH_CAPABILITIES from
> feature_word_info[FEAT_7_0_EDX].unmigratable_flags.
> 
> This series is necessary for that, be I think we still can't let
> the VM be migrated if arch-capabilities is enabled and we're
> running on a host that doesn't have MSR_IA32_ARCH_CAPABILITIES on
> kvm_feature_msrs.
> 
> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
> 
> > ---
> >  target/i386/cpu.c | 31 ++++++++++++++++++++++++++++++-
> >  target/i386/cpu.h |  8 ++++++++
> >  target/i386/kvm.c | 11 +++++++++++
> >  3 files changed, 49 insertions(+), 1 deletion(-)
> > 
[...]
> >  
> >  typedef struct X86RegisterInfo32 {
> > @@ -3696,7 +3717,15 @@ static uint32_t
> > x86_cpu_get_supported_feature_word(FeatureWord w,
> >                                                          wi-
> > >cpuid.reg);
> >              break;
> >          case MSR_FEATURE_WORD:
> > -            r = kvm_arch_get_supported_msr_feature(kvm_state, wi-
> > >msr.index);
> > +            /* Special case:
> > +             * No matter host status, IA32_ARCH_CAPABILITIES.RSBA
> > [bit 2]
> > +             * is always supported in guest.
> > +             */
> > +            if (wi->msr.index == MSR_IA32_ARCH_CAPABILITIES) {
> > +                r = MSR_ARCH_CAP_RSBA;
> > +            }
> > +            r |= kvm_arch_get_supported_msr_feature(kvm_state,
> > +                        wi->msr.index);
> >              break;
After I add the filtering out MSR feature, whose CPUID dependency fails
, in x86_cpu_filter_features(), 1 issue comes out here: 

If running on an old platform that doesn't have ARCH_CAPABILITIES MSR,
but we still pretends it here, then qemu will always print out
"warning: host doesn't support requested feature: MSR(10AH).rsba [bit
2]", with -cpu 'host', which does not look comfortable.
How about remove this hunk for now? leave it to when we fully decide
how to handle ARCH_CAPABILITIES live-migration safely. 
> >          }
> >      } else if (hvf_enabled()) {
[...]
Re: [Qemu-devel] [PATCH v5 3/3] x86: define a new MSR based feature word -- FEATURE_WORDS_ARCH_CAPABILITIES
Posted by Eduardo Habkost 7 years ago 
On Fri, Oct 26, 2018 at 11:01:25AM +0800, Robert Hoo wrote:
> On Wed, 2018-10-24 at 07:06 -0300, Eduardo Habkost wrote:
> > On Mon, Oct 15, 2018 at 12:47:25PM +0800, Robert Hoo wrote:
> > > Note RSBA is specially treated -- no matter host support it or not,
> > > qemu
> > > pretends it is supported.
> > > 
> > > Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
> > 
> > I am now wondering what else we need to be able to remove
> > CPUID_7_0_EDX_ARCH_CAPABILITIES from
> > feature_word_info[FEAT_7_0_EDX].unmigratable_flags.
> > 
> > This series is necessary for that, be I think we still can't let
> > the VM be migrated if arch-capabilities is enabled and we're
> > running on a host that doesn't have MSR_IA32_ARCH_CAPABILITIES on
> > kvm_feature_msrs.
> > 
> > Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
> > 
> > > ---
> > >  target/i386/cpu.c | 31 ++++++++++++++++++++++++++++++-
> > >  target/i386/cpu.h |  8 ++++++++
> > >  target/i386/kvm.c | 11 +++++++++++
> > >  3 files changed, 49 insertions(+), 1 deletion(-)
> > > 
> [...]
> > >  
> > >  typedef struct X86RegisterInfo32 {
> > > @@ -3696,7 +3717,15 @@ static uint32_t
> > > x86_cpu_get_supported_feature_word(FeatureWord w,
> > >                                                          wi-
> > > >cpuid.reg);
> > >              break;
> > >          case MSR_FEATURE_WORD:
> > > -            r = kvm_arch_get_supported_msr_feature(kvm_state, wi-
> > > >msr.index);
> > > +            /* Special case:
> > > +             * No matter host status, IA32_ARCH_CAPABILITIES.RSBA
> > > [bit 2]
> > > +             * is always supported in guest.
> > > +             */
> > > +            if (wi->msr.index == MSR_IA32_ARCH_CAPABILITIES) {
> > > +                r = MSR_ARCH_CAP_RSBA;
> > > +            }
> > > +            r |= kvm_arch_get_supported_msr_feature(kvm_state,
> > > +                        wi->msr.index);
> > >              break;
> After I add the filtering out MSR feature, whose CPUID dependency fails
> , in x86_cpu_filter_features(), 1 issue comes out here: 
> 
> If running on an old platform that doesn't have ARCH_CAPABILITIES MSR,
> but we still pretends it here, then qemu will always print out
> "warning: host doesn't support requested feature: MSR(10AH).rsba [bit
> 2]", with -cpu 'host', which does not look comfortable.
> How about remove this hunk for now? leave it to when we fully decide
> how to handle ARCH_CAPABILITIES live-migration safely. 

I will remove that hunk in x86-next, thanks for noting!

-- 
Eduardo

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