* [PATCH 2/4] hyperv: uapi: Add bit for nested virtualization
2026-02-18 14:47 [PATCH 1/4] mshv: Add nested virtualization creation flag Anatol Belski
@ 2026-02-18 14:48 ` Anatol Belski
2026-02-18 14:48 ` [PATCH 3/4] drivers: hv: enable " Anatol Belski
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Anatol Belski @ 2026-02-18 14:48 UTC (permalink / raw)
To: linux-hyperv; +Cc: wei.liu, muislam
From: Muminul Islam <muislam@microsoft.com>
Add a new bit for nested virtualization creation flag.
This is exposed to user-space API to enable during partition
creation.
Signed-off-by: Muminul Islam <muislam@microsoft.com>
---
include/uapi/linux/mshv.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/uapi/linux/mshv.h b/include/uapi/linux/mshv.h
index dee3ece28ce5..7ef5dd67a232 100644
--- a/include/uapi/linux/mshv.h
+++ b/include/uapi/linux/mshv.h
@@ -27,6 +27,7 @@ enum {
MSHV_PT_BIT_X2APIC,
MSHV_PT_BIT_GPA_SUPER_PAGES,
MSHV_PT_BIT_CPU_AND_XSAVE_FEATURES,
+ MSHV_PT_BIT_NESTED_VIRTUALIZATION,
MSHV_PT_BIT_COUNT,
};
--
2.34.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 3/4] drivers: hv: enable nested virtualization
2026-02-18 14:47 [PATCH 1/4] mshv: Add nested virtualization creation flag Anatol Belski
2026-02-18 14:48 ` [PATCH 2/4] hyperv: uapi: Add bit for nested virtualization Anatol Belski
@ 2026-02-18 14:48 ` Anatol Belski
2026-02-18 14:48 ` [PATCH 4/4] mshv: Add SMT_ENABLED_GUEST partition creation flag Anatol Belski
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Anatol Belski @ 2026-02-18 14:48 UTC (permalink / raw)
To: linux-hyperv; +Cc: wei.liu, muislam
From: Muminul Islam <muislam@microsoft.com>
Based on the bits provided by VMM, enable the nested
virtualization in the partition creation flag.
Signed-off-by: Muminul Islam <muislam@microsoft.com>
---
drivers/hv/mshv_root_main.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index 681b58154d5e..fb3ade44e1f1 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -1921,6 +1921,8 @@ static long mshv_ioctl_process_pt_flags(void __user *user_arg, u64 *pt_flags,
*pt_flags |= HV_PARTITION_CREATION_FLAG_X2APIC_CAPABLE;
if (args.pt_flags & BIT_ULL(MSHV_PT_BIT_GPA_SUPER_PAGES))
*pt_flags |= HV_PARTITION_CREATION_FLAG_GPA_SUPER_PAGES_ENABLED;
+ if (args.pt_flags & BIT(MSHV_PT_BIT_NESTED_VIRTUALIZATION))
+ *pt_flags |= HV_PARTITION_CREATION_FLAG_NESTED_VIRTUALIZATION_CAPABLE;
isol_props->as_uint64 = 0;
--
2.34.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 4/4] mshv: Add SMT_ENABLED_GUEST partition creation flag
2026-02-18 14:47 [PATCH 1/4] mshv: Add nested virtualization creation flag Anatol Belski
2026-02-18 14:48 ` [PATCH 2/4] hyperv: uapi: Add bit for nested virtualization Anatol Belski
2026-02-18 14:48 ` [PATCH 3/4] drivers: hv: enable " Anatol Belski
@ 2026-02-18 14:48 ` Anatol Belski
2026-02-18 17:09 ` [PATCH 1/4] mshv: Add nested virtualization " Easwar Hariharan
2026-02-18 23:55 ` Wei Liu
4 siblings, 0 replies; 6+ messages in thread
From: Anatol Belski @ 2026-02-18 14:48 UTC (permalink / raw)
To: linux-hyperv; +Cc: wei.liu, muislam
Add support for HV_PARTITION_CREATION_FLAG_SMT_ENABLED_GUEST
to allow userspace VMMs to enable SMT for guest partitions.
Expose this via new MSHV_PT_BIT_SMT_ENABLED_GUEST flag in the UAPI.
Withouth this flag, the hypervisor schedules guest VPs incorrectly,
causing SMT unusable.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
---
drivers/hv/mshv_root_main.c | 2 ++
include/hyperv/hvhdk.h | 1 +
include/uapi/linux/mshv.h | 1 +
3 files changed, 4 insertions(+)
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index fb3ade44e1f1..899e055d975f 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -1923,6 +1923,8 @@ static long mshv_ioctl_process_pt_flags(void __user *user_arg, u64 *pt_flags,
*pt_flags |= HV_PARTITION_CREATION_FLAG_GPA_SUPER_PAGES_ENABLED;
if (args.pt_flags & BIT(MSHV_PT_BIT_NESTED_VIRTUALIZATION))
*pt_flags |= HV_PARTITION_CREATION_FLAG_NESTED_VIRTUALIZATION_CAPABLE;
+ if (args.pt_flags & BIT(MSHV_PT_BIT_SMT_ENABLED_GUEST))
+ *pt_flags |= HV_PARTITION_CREATION_FLAG_SMT_ENABLED_GUEST;
isol_props->as_uint64 = 0;
diff --git a/include/hyperv/hvhdk.h b/include/hyperv/hvhdk.h
index 03afb7d0412b..331cebc471e1 100644
--- a/include/hyperv/hvhdk.h
+++ b/include/hyperv/hvhdk.h
@@ -328,6 +328,7 @@ union hv_partition_isolation_properties {
#define HV_PARTITION_ISOLATION_HOST_TYPE_RESERVED 0x2
/* Note: Exo partition is enabled by default */
+#define HV_PARTITION_CREATION_FLAG_SMT_ENABLED_GUEST BIT(0)
#define HV_PARTITION_CREATION_FLAG_NESTED_VIRTUALIZATION_CAPABLE BIT(1)
#define HV_PARTITION_CREATION_FLAG_GPA_SUPER_PAGES_ENABLED BIT(4)
#define HV_PARTITION_CREATION_FLAG_EXO_PARTITION BIT(8)
diff --git a/include/uapi/linux/mshv.h b/include/uapi/linux/mshv.h
index 7ef5dd67a232..e0645a34b55b 100644
--- a/include/uapi/linux/mshv.h
+++ b/include/uapi/linux/mshv.h
@@ -28,6 +28,7 @@ enum {
MSHV_PT_BIT_GPA_SUPER_PAGES,
MSHV_PT_BIT_CPU_AND_XSAVE_FEATURES,
MSHV_PT_BIT_NESTED_VIRTUALIZATION,
+ MSHV_PT_BIT_SMT_ENABLED_GUEST,
MSHV_PT_BIT_COUNT,
};
--
2.34.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH 1/4] mshv: Add nested virtualization creation flag
2026-02-18 14:47 [PATCH 1/4] mshv: Add nested virtualization creation flag Anatol Belski
` (2 preceding siblings ...)
2026-02-18 14:48 ` [PATCH 4/4] mshv: Add SMT_ENABLED_GUEST partition creation flag Anatol Belski
@ 2026-02-18 17:09 ` Easwar Hariharan
2026-02-18 23:55 ` Wei Liu
4 siblings, 0 replies; 6+ messages in thread
From: Easwar Hariharan @ 2026-02-18 17:09 UTC (permalink / raw)
To: Anatol Belski; +Cc: linux-hyperv, easwar.hariharan, wei.liu, muislam
On 2/18/2026 6:47 AM, Anatol Belski wrote:
> From: Muminul Islam <muislam@microsoft.com>
>
> Introduce HV_PARTITION_CREATION_FLAG_NESTED_VIRTUALIZATION_CAPABLE to
> indicate support for nested virtualization during partition creation.
>
> This enables clearer configuration and capability checks for nested
> virtualization scenarios.
>
> Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
> Signed-off-by: Muminul Islam <muislam@microsoft.com>
> ---
> include/hyperv/hvhdk.h | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/include/hyperv/hvhdk.h b/include/hyperv/hvhdk.h
> index 08965970c17d..03afb7d0412b 100644
> --- a/include/hyperv/hvhdk.h
> +++ b/include/hyperv/hvhdk.h
> @@ -328,6 +328,7 @@ union hv_partition_isolation_properties {
> #define HV_PARTITION_ISOLATION_HOST_TYPE_RESERVED 0x2
>
> /* Note: Exo partition is enabled by default */
> +#define HV_PARTITION_CREATION_FLAG_NESTED_VIRTUALIZATION_CAPABLE BIT(1)
> #define HV_PARTITION_CREATION_FLAG_GPA_SUPER_PAGES_ENABLED BIT(4)
> #define HV_PARTITION_CREATION_FLAG_EXO_PARTITION BIT(8)
> #define HV_PARTITION_CREATION_FLAG_LAPIC_ENABLED BIT(13)
Patches 1, 2, and 3 can all be squashed into 1 patch.
Thanks,
Easwar (he/him)
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH 1/4] mshv: Add nested virtualization creation flag
2026-02-18 14:47 [PATCH 1/4] mshv: Add nested virtualization creation flag Anatol Belski
` (3 preceding siblings ...)
2026-02-18 17:09 ` [PATCH 1/4] mshv: Add nested virtualization " Easwar Hariharan
@ 2026-02-18 23:55 ` Wei Liu
4 siblings, 0 replies; 6+ messages in thread
From: Wei Liu @ 2026-02-18 23:55 UTC (permalink / raw)
To: Anatol Belski; +Cc: linux-hyperv, wei.liu, muislam
On Wed, Feb 18, 2026 at 02:47:59PM +0000, Anatol Belski wrote:
> From: Muminul Islam <muislam@microsoft.com>
>
> Introduce HV_PARTITION_CREATION_FLAG_NESTED_VIRTUALIZATION_CAPABLE to
> indicate support for nested virtualization during partition creation.
>
> This enables clearer configuration and capability checks for nested
> virtualization scenarios.
>
> Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
> Signed-off-by: Muminul Islam <muislam@microsoft.com>
Series applied. I squashed the first three patches into one.
Wei
^ permalink raw reply [flat|nested] 6+ messages in thread