[PATCH v4 0/2] Add support for LAM in QEMU

[PATCH v4 0/2] Add support for LAM in QEMU

[Binbin Wu]

Linear-address masking (LAM) [1], modifies the checking that is applied to
*64-bit* linear addresses, allowing software to use of the untranslated
address bits for metadata and masks the metadata bits before using them as
linear addresses to access memory.

When the feature is virtualized and exposed to guest, it can be used for 
efficient
address sanitizers (ASAN) implementation and for optimizations in JITs and 
virtual machines.

The KVM patch series can be found in [2].

[1] Intel ISE https://cdrdv2.intel.com/v1/dl/getContent/671368
    Chapter Linear Address Masking (LAM)
[2] https://lore.kernel.org/kvm/20230913124227.12574-1-binbin.wu@linux.intel.com

---
Changelog
v4:
- Add a reviewed-by from Xiaoyao for patch 1.
- Mask out LAM bit on CR4 if vcpu doesn't support LAM in cpu_x86_update_cr4() (Xiaoyao)

v3:
- https://lists.gnu.org/archive/html/qemu-devel/2023-07/msg04160.html

Binbin Wu (1):
  target/i386: add control bits support for LAM

Robert Hoo (1):
  target/i386: add support for LAM in CPUID enumeration

 target/i386/cpu.c    | 2 +-
 target/i386/cpu.h    | 9 ++++++++-
 target/i386/helper.c | 4 ++++
 3 files changed, 13 insertions(+), 2 deletions(-)


base-commit: f614acb7450282a119d85d759f27eae190476058
-- 
2.25.1

[PATCH v4 1/2] target/i386: add support for LAM in CPUID enumeration

[Binbin Wu]

From: Robert Hoo <robert.hu@linux.intel.com>

Linear Address Masking (LAM) is a new Intel CPU feature, which allows
software to use of the untranslated address bits for metadata.

The bit definition:
CPUID.(EAX=7,ECX=1):EAX[26]

Add CPUID definition for LAM.

Note LAM feature is not supported for TCG of target-i386, LAM CPIUD bit
will not be added to TCG_7_1_EAX_FEATURES.

More info can be found in Intel ISE Chapter "LINEAR ADDRESS MASKING(LAM)"
https://cdrdv2.intel.com/v1/dl/getContent/671368

Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
Co-developed-by: Binbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
 target/i386/cpu.c | 2 +-
 target/i386/cpu.h | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 2524881ce2..fc862dfeb1 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -967,7 +967,7 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
             "fsrc", NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
             NULL, "amx-fp16", NULL, "avx-ifma",
-            NULL, NULL, NULL, NULL,
+            NULL, NULL, "lam", NULL,
             NULL, NULL, NULL, NULL,
         },
         .cpuid = {
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 7f0786e8b9..18ea755644 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -925,6 +925,8 @@ uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
 #define CPUID_7_1_EAX_AMX_FP16          (1U << 21)
 /* Support for VPMADD52[H,L]UQ */
 #define CPUID_7_1_EAX_AVX_IFMA          (1U << 23)
+/* Linear Address Masking */
+#define CPUID_7_1_EAX_LAM               (1U << 26)
 
 /* Support for VPDPB[SU,UU,SS]D[,S] */
 #define CPUID_7_1_EDX_AVX_VNNI_INT8     (1U << 4)
-- 
2.25.1

[PATCH v4 2/2] target/i386: add control bits support for LAM

[Binbin Wu]

LAM uses CR3[61] and CR3[62] to configure/enable LAM on user pointers.
LAM uses CR4[28] to configure/enable LAM on supervisor pointers.

For CR3 LAM bits, no additional handling needed:
- TCG
  LAM is not supported for TCG of target-i386.  helper_write_crN() and
  helper_vmrun() check max physical address bits before calling
  cpu_x86_update_cr3(), no change needed, i.e. CR3 LAM bits are not allowed
  to be set in TCG.
- gdbstub
  x86_cpu_gdb_write_register() will call cpu_x86_update_cr3() to update cr3.
  Allow gdb to set the LAM bit(s) to CR3, if vcpu doesn't support LAM,
  KVM_SET_SREGS will fail as other reserved bits.

For CR4 LAM bit, its reservation depends on vcpu supporting LAM feature or
not.
- TCG
  LAM is not supported for TCG of target-i386.  helper_write_crN() and
  helper_vmrun() check CR4 reserved bit before calling cpu_x86_update_cr4(),
  i.e. CR4 LAM bit is not allowed to be set in TCG.
- gdbstub
  x86_cpu_gdb_write_register() will call cpu_x86_update_cr4() to update cr4.
  Mask out LAM bit on CR4 if vcpu doesn't support LAM.
- x86_cpu_reset_hold() doesn't need special handling.

Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
---
 target/i386/cpu.h    | 7 ++++++-
 target/i386/helper.c | 4 ++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 18ea755644..598a3fa140 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -261,6 +261,7 @@ typedef enum X86Seg {
 #define CR4_SMAP_MASK   (1U << 21)
 #define CR4_PKE_MASK   (1U << 22)
 #define CR4_PKS_MASK   (1U << 24)
+#define CR4_LAM_SUP_MASK (1U << 28)
 
 #define CR4_RESERVED_MASK \
 (~(target_ulong)(CR4_VME_MASK | CR4_PVI_MASK | CR4_TSD_MASK \
@@ -269,7 +270,8 @@ typedef enum X86Seg {
                 | CR4_OSFXSR_MASK | CR4_OSXMMEXCPT_MASK | CR4_UMIP_MASK \
                 | CR4_LA57_MASK \
                 | CR4_FSGSBASE_MASK | CR4_PCIDE_MASK | CR4_OSXSAVE_MASK \
-                | CR4_SMEP_MASK | CR4_SMAP_MASK | CR4_PKE_MASK | CR4_PKS_MASK))
+                | CR4_SMEP_MASK | CR4_SMAP_MASK | CR4_PKE_MASK | CR4_PKS_MASK \
+                | CR4_LAM_SUP_MASK))
 
 #define DR6_BD          (1 << 13)
 #define DR6_BS          (1 << 14)
@@ -2522,6 +2524,9 @@ static inline uint64_t cr4_reserved_bits(CPUX86State *env)
     if (!(env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_PKS)) {
         reserved_bits |= CR4_PKS_MASK;
     }
+    if (!(env->features[FEAT_7_1_EAX] & CPUID_7_1_EAX_LAM)) {
+        reserved_bits |= CR4_LAM_SUP_MASK;
+    }
     return reserved_bits;
 }
 
diff --git a/target/i386/helper.c b/target/i386/helper.c
index 2070dd0dda..1da7a7d315 100644
--- a/target/i386/helper.c
+++ b/target/i386/helper.c
@@ -219,6 +219,10 @@ void cpu_x86_update_cr4(CPUX86State *env, uint32_t new_cr4)
         new_cr4 &= ~CR4_PKS_MASK;
     }
 
+    if (!(env->features[FEAT_7_1_EAX] & CPUID_7_1_EAX_LAM)) {
+        new_cr4 &= ~CR4_LAM_SUP_MASK;
+    }
+
     env->cr[4] = new_cr4;
     env->hflags = hflags;
 
-- 
2.25.1

Re: [PATCH v4 2/2] target/i386: add control bits support for LAM

[Xiaoyao Li]

On 1/12/2024 2:00 PM, Binbin Wu wrote:
> LAM uses CR3[61] and CR3[62] to configure/enable LAM on user pointers.
> LAM uses CR4[28] to configure/enable LAM on supervisor pointers.
> 
> For CR3 LAM bits, no additional handling needed:
> - TCG
>    LAM is not supported for TCG of target-i386.  helper_write_crN() and
>    helper_vmrun() check max physical address bits before calling
>    cpu_x86_update_cr3(), no change needed, i.e. CR3 LAM bits are not allowed
>    to be set in TCG.
> - gdbstub
>    x86_cpu_gdb_write_register() will call cpu_x86_update_cr3() to update cr3.
>    Allow gdb to set the LAM bit(s) to CR3, if vcpu doesn't support LAM,
>    KVM_SET_SREGS will fail as other reserved bits.
> 
> For CR4 LAM bit, its reservation depends on vcpu supporting LAM feature or
> not.
> - TCG
>    LAM is not supported for TCG of target-i386.  helper_write_crN() and
>    helper_vmrun() check CR4 reserved bit before calling cpu_x86_update_cr4(),
>    i.e. CR4 LAM bit is not allowed to be set in TCG.
> - gdbstub
>    x86_cpu_gdb_write_register() will call cpu_x86_update_cr4() to update cr4.
>    Mask out LAM bit on CR4 if vcpu doesn't support LAM.
> - x86_cpu_reset_hold() doesn't need special handling.
> 
> Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
> Tested-by: Xuelian Guo <xuelian.guo@intel.com>

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>

> ---
>   target/i386/cpu.h    | 7 ++++++-
>   target/i386/helper.c | 4 ++++
>   2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 18ea755644..598a3fa140 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -261,6 +261,7 @@ typedef enum X86Seg {
>   #define CR4_SMAP_MASK   (1U << 21)
>   #define CR4_PKE_MASK   (1U << 22)
>   #define CR4_PKS_MASK   (1U << 24)
> +#define CR4_LAM_SUP_MASK (1U << 28)
>   
>   #define CR4_RESERVED_MASK \
>   (~(target_ulong)(CR4_VME_MASK | CR4_PVI_MASK | CR4_TSD_MASK \
> @@ -269,7 +270,8 @@ typedef enum X86Seg {
>                   | CR4_OSFXSR_MASK | CR4_OSXMMEXCPT_MASK | CR4_UMIP_MASK \
>                   | CR4_LA57_MASK \
>                   | CR4_FSGSBASE_MASK | CR4_PCIDE_MASK | CR4_OSXSAVE_MASK \
> -                | CR4_SMEP_MASK | CR4_SMAP_MASK | CR4_PKE_MASK | CR4_PKS_MASK))
> +                | CR4_SMEP_MASK | CR4_SMAP_MASK | CR4_PKE_MASK | CR4_PKS_MASK \
> +                | CR4_LAM_SUP_MASK))
>   
>   #define DR6_BD          (1 << 13)
>   #define DR6_BS          (1 << 14)
> @@ -2522,6 +2524,9 @@ static inline uint64_t cr4_reserved_bits(CPUX86State *env)
>       if (!(env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_PKS)) {
>           reserved_bits |= CR4_PKS_MASK;
>       }
> +    if (!(env->features[FEAT_7_1_EAX] & CPUID_7_1_EAX_LAM)) {
> +        reserved_bits |= CR4_LAM_SUP_MASK;
> +    }
>       return reserved_bits;
>   }
>   
> diff --git a/target/i386/helper.c b/target/i386/helper.c
> index 2070dd0dda..1da7a7d315 100644
> --- a/target/i386/helper.c
> +++ b/target/i386/helper.c
> @@ -219,6 +219,10 @@ void cpu_x86_update_cr4(CPUX86State *env, uint32_t new_cr4)
>           new_cr4 &= ~CR4_PKS_MASK;
>       }
>   
> +    if (!(env->features[FEAT_7_1_EAX] & CPUID_7_1_EAX_LAM)) {
> +        new_cr4 &= ~CR4_LAM_SUP_MASK;
> +    }
> +
>       env->cr[4] = new_cr4;
>       env->hflags = hflags;
>   

Re: [PATCH v4 0/2] Add support for LAM in QEMU

[Binbin Wu]

Gentle ping...
Please help to review and consider applying the patch series. (The KVM
part has been merged).


On 1/12/2024 2:00 PM, Binbin Wu wrote:
> Linear-address masking (LAM) [1], modifies the checking that is applied to
> *64-bit* linear addresses, allowing software to use of the untranslated
> address bits for metadata and masks the metadata bits before using them as
> linear addresses to access memory.
>
> When the feature is virtualized and exposed to guest, it can be used for
> efficient
> address sanitizers (ASAN) implementation and for optimizations in JITs and
> virtual machines.
>
> The KVM patch series can be found in [2].
>
> [1] Intel ISE https://cdrdv2.intel.com/v1/dl/getContent/671368
>      Chapter Linear Address Masking (LAM)
> [2] https://lore.kernel.org/kvm/20230913124227.12574-1-binbin.wu@linux.intel.com
>
> ---
> Changelog
> v4:
> - Add a reviewed-by from Xiaoyao for patch 1.
> - Mask out LAM bit on CR4 if vcpu doesn't support LAM in cpu_x86_update_cr4() (Xiaoyao)
>
> v3:
> - https://lists.gnu.org/archive/html/qemu-devel/2023-07/msg04160.html
>
> Binbin Wu (1):
>    target/i386: add control bits support for LAM
>
> Robert Hoo (1):
>    target/i386: add support for LAM in CPUID enumeration
>
>   target/i386/cpu.c    | 2 +-
>   target/i386/cpu.h    | 9 ++++++++-
>   target/i386/helper.c | 4 ++++
>   3 files changed, 13 insertions(+), 2 deletions(-)
>
>
> base-commit: f614acb7450282a119d85d759f27eae190476058

Re: [PATCH v4 0/2] Add support for LAM in QEMU

[Binbin Wu]

Ping...

Hi Paolo,
do you have time to have a look at this patchset?


On 1/22/2024 4:55 PM, Binbin Wu wrote:
> Gentle ping...
> Please help to review and consider applying the patch series. (The KVM
> part has been merged).
>
>
> On 1/12/2024 2:00 PM, Binbin Wu wrote:
>> Linear-address masking (LAM) [1], modifies the checking that is 
>> applied to
>> *64-bit* linear addresses, allowing software to use of the untranslated
>> address bits for metadata and masks the metadata bits before using 
>> them as
>> linear addresses to access memory.
>>
>> When the feature is virtualized and exposed to guest, it can be used for
>> efficient
>> address sanitizers (ASAN) implementation and for optimizations in 
>> JITs and
>> virtual machines.
>>
>> The KVM patch series can be found in [2].
>>
>> [1] Intel ISE https://cdrdv2.intel.com/v1/dl/getContent/671368
>>      Chapter Linear Address Masking (LAM)
>> [2] 
>> https://lore.kernel.org/kvm/20230913124227.12574-1-binbin.wu@linux.intel.com
>>
>> ---
>> Changelog
>> v4:
>> - Add a reviewed-by from Xiaoyao for patch 1.
>> - Mask out LAM bit on CR4 if vcpu doesn't support LAM in 
>> cpu_x86_update_cr4() (Xiaoyao)
>>
>> v3:
>> - https://lists.gnu.org/archive/html/qemu-devel/2023-07/msg04160.html
>>
>> Binbin Wu (1):
>>    target/i386: add control bits support for LAM
>>
>> Robert Hoo (1):
>>    target/i386: add support for LAM in CPUID enumeration
>>
>>   target/i386/cpu.c    | 2 +-
>>   target/i386/cpu.h    | 9 ++++++++-
>>   target/i386/helper.c | 4 ++++
>>   3 files changed, 13 insertions(+), 2 deletions(-)
>>
>>
>> base-commit: f614acb7450282a119d85d759f27eae190476058
>

Re: [PATCH v4 1/2] target/i386: add support for LAM in CPUID enumeration

[Zhao Liu]

On Fri, Jan 12, 2024 at 02:00:41PM +0800, Binbin Wu wrote:
> Date: Fri, 12 Jan 2024 14:00:41 +0800
> From: Binbin Wu <binbin.wu@linux.intel.com>
> Subject: [PATCH v4 1/2] target/i386: add support for LAM in CPUID
>  enumeration
> X-Mailer: git-send-email 2.25.1
> 
> From: Robert Hoo <robert.hu@linux.intel.com>
> 
> Linear Address Masking (LAM) is a new Intel CPU feature, which allows
> software to use of the untranslated address bits for metadata.
> 
> The bit definition:
> CPUID.(EAX=7,ECX=1):EAX[26]
> 
> Add CPUID definition for LAM.
> 
> Note LAM feature is not supported for TCG of target-i386, LAM CPIUD bit
> will not be added to TCG_7_1_EAX_FEATURES.
> 
> More info can be found in Intel ISE Chapter "LINEAR ADDRESS MASKING(LAM)"
> https://cdrdv2.intel.com/v1/dl/getContent/671368
> 
> Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
> Co-developed-by: Binbin Wu <binbin.wu@linux.intel.com>
> Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
> Tested-by: Xuelian Guo <xuelian.guo@intel.com>
> Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
> ---
>  target/i386/cpu.c | 2 +-
>  target/i386/cpu.h | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>

> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 2524881ce2..fc862dfeb1 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -967,7 +967,7 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
>              "fsrc", NULL, NULL, NULL,
>              NULL, NULL, NULL, NULL,
>              NULL, "amx-fp16", NULL, "avx-ifma",
> -            NULL, NULL, NULL, NULL,
> +            NULL, NULL, "lam", NULL,
>              NULL, NULL, NULL, NULL,
>          },
>          .cpuid = {
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 7f0786e8b9..18ea755644 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -925,6 +925,8 @@ uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
>  #define CPUID_7_1_EAX_AMX_FP16          (1U << 21)
>  /* Support for VPMADD52[H,L]UQ */
>  #define CPUID_7_1_EAX_AVX_IFMA          (1U << 23)
> +/* Linear Address Masking */
> +#define CPUID_7_1_EAX_LAM               (1U << 26)
>  
>  /* Support for VPDPB[SU,UU,SS]D[,S] */
>  #define CPUID_7_1_EDX_AVX_VNNI_INT8     (1U << 4)
> -- 
> 2.25.1
> 
> 

Re: [PATCH v4 2/2] target/i386: add control bits support for LAM

[Zhao Liu]

On Fri, Jan 12, 2024 at 02:00:42PM +0800, Binbin Wu wrote:
> Date: Fri, 12 Jan 2024 14:00:42 +0800
> From: Binbin Wu <binbin.wu@linux.intel.com>
> Subject: [PATCH v4 2/2] target/i386: add control bits support for LAM
> X-Mailer: git-send-email 2.25.1
> 
> LAM uses CR3[61] and CR3[62] to configure/enable LAM on user pointers.
> LAM uses CR4[28] to configure/enable LAM on supervisor pointers.
> 
> For CR3 LAM bits, no additional handling needed:
> - TCG
>   LAM is not supported for TCG of target-i386.  helper_write_crN() and
>   helper_vmrun() check max physical address bits before calling
>   cpu_x86_update_cr3(), no change needed, i.e. CR3 LAM bits are not allowed
>   to be set in TCG.
> - gdbstub
>   x86_cpu_gdb_write_register() will call cpu_x86_update_cr3() to update cr3.
>   Allow gdb to set the LAM bit(s) to CR3, if vcpu doesn't support LAM,
>   KVM_SET_SREGS will fail as other reserved bits.
> 
> For CR4 LAM bit, its reservation depends on vcpu supporting LAM feature or
> not.
> - TCG
>   LAM is not supported for TCG of target-i386.  helper_write_crN() and
>   helper_vmrun() check CR4 reserved bit before calling cpu_x86_update_cr4(),
>   i.e. CR4 LAM bit is not allowed to be set in TCG.
> - gdbstub
>   x86_cpu_gdb_write_register() will call cpu_x86_update_cr4() to update cr4.
>   Mask out LAM bit on CR4 if vcpu doesn't support LAM.
> - x86_cpu_reset_hold() doesn't need special handling.
> 
> Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
> Tested-by: Xuelian Guo <xuelian.guo@intel.com>
> ---
>  target/i386/cpu.h    | 7 ++++++-
>  target/i386/helper.c | 4 ++++
>  2 files changed, 10 insertions(+), 1 deletion(-)

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>

> 
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 18ea755644..598a3fa140 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -261,6 +261,7 @@ typedef enum X86Seg {
>  #define CR4_SMAP_MASK   (1U << 21)
>  #define CR4_PKE_MASK   (1U << 22)
>  #define CR4_PKS_MASK   (1U << 24)
> +#define CR4_LAM_SUP_MASK (1U << 28)
>  
>  #define CR4_RESERVED_MASK \
>  (~(target_ulong)(CR4_VME_MASK | CR4_PVI_MASK | CR4_TSD_MASK \
> @@ -269,7 +270,8 @@ typedef enum X86Seg {
>                  | CR4_OSFXSR_MASK | CR4_OSXMMEXCPT_MASK | CR4_UMIP_MASK \
>                  | CR4_LA57_MASK \
>                  | CR4_FSGSBASE_MASK | CR4_PCIDE_MASK | CR4_OSXSAVE_MASK \
> -                | CR4_SMEP_MASK | CR4_SMAP_MASK | CR4_PKE_MASK | CR4_PKS_MASK))
> +                | CR4_SMEP_MASK | CR4_SMAP_MASK | CR4_PKE_MASK | CR4_PKS_MASK \
> +                | CR4_LAM_SUP_MASK))
>  
>  #define DR6_BD          (1 << 13)
>  #define DR6_BS          (1 << 14)
> @@ -2522,6 +2524,9 @@ static inline uint64_t cr4_reserved_bits(CPUX86State *env)
>      if (!(env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_PKS)) {
>          reserved_bits |= CR4_PKS_MASK;
>      }
> +    if (!(env->features[FEAT_7_1_EAX] & CPUID_7_1_EAX_LAM)) {
> +        reserved_bits |= CR4_LAM_SUP_MASK;
> +    }
>      return reserved_bits;
>  }
>  
> diff --git a/target/i386/helper.c b/target/i386/helper.c
> index 2070dd0dda..1da7a7d315 100644
> --- a/target/i386/helper.c
> +++ b/target/i386/helper.c
> @@ -219,6 +219,10 @@ void cpu_x86_update_cr4(CPUX86State *env, uint32_t new_cr4)
>          new_cr4 &= ~CR4_PKS_MASK;
>      }
>  
> +    if (!(env->features[FEAT_7_1_EAX] & CPUID_7_1_EAX_LAM)) {
> +        new_cr4 &= ~CR4_LAM_SUP_MASK;
> +    }
> +
>      env->cr[4] = new_cr4;
>      env->hflags = hflags;
>  
> -- 
> 2.25.1
> 
> 

Re: [PATCH v4 0/2] Add support for LAM in QEMU

[Binbin Wu]

Ping...

On 1/22/2024 4:55 PM, Binbin Wu wrote:
> Gentle ping...
> Please help to review and consider applying the patch series. (The KVM
> part has been merged).
>
>
> On 1/12/2024 2:00 PM, Binbin Wu wrote:
>> Linear-address masking (LAM) [1], modifies the checking that is 
>> applied to
>> *64-bit* linear addresses, allowing software to use of the untranslated
>> address bits for metadata and masks the metadata bits before using 
>> them as
>> linear addresses to access memory.
>>
>> When the feature is virtualized and exposed to guest, it can be used for
>> efficient
>> address sanitizers (ASAN) implementation and for optimizations in 
>> JITs and
>> virtual machines.
>>
>> The KVM patch series can be found in [2].
>>
>> [1] Intel ISE https://cdrdv2.intel.com/v1/dl/getContent/671368
>>      Chapter Linear Address Masking (LAM)
>> [2] 
>> https://lore.kernel.org/kvm/20230913124227.12574-1-binbin.wu@linux.intel.com
>>
>> ---
>> Changelog
>> v4:
>> - Add a reviewed-by from Xiaoyao for patch 1.
>> - Mask out LAM bit on CR4 if vcpu doesn't support LAM in 
>> cpu_x86_update_cr4() (Xiaoyao)
>>
>> v3:
>> - https://lists.gnu.org/archive/html/qemu-devel/2023-07/msg04160.html
>>
>> Binbin Wu (1):
>>    target/i386: add control bits support for LAM
>>
>> Robert Hoo (1):
>>    target/i386: add support for LAM in CPUID enumeration
>>
>>   target/i386/cpu.c    | 2 +-
>>   target/i386/cpu.h    | 9 ++++++++-
>>   target/i386/helper.c | 4 ++++
>>   3 files changed, 13 insertions(+), 2 deletions(-)
>>
>>
>> base-commit: f614acb7450282a119d85d759f27eae190476058
>

Re: [PATCH v4 0/2] Add support for LAM in QEMU

[Paolo Bonzini]

Queued, thanks.

Paolo

Re: [PATCH v4 0/2] Add support for LAM in QEMU

[Paolo Bonzini]

Queued, thanks.

Paolo