[PATCH v3 0/5] mshv: Fixes for stats and vp state page mappings

[PATCH v3 0/5] mshv: Fixes for stats and vp state page mappings

[Nuno Das Neves]

There are some differences in how L1VH partitions must map stats and vp
state pages, some of which are due to differences across hypervisor
versions. Detect and handle these cases.

Patch 1:
Fix for the logic of when to map the vp stats page for the root scheduler.

Patch 2-3:
Add HVCALL_GET_PARTITION_PROPERTY_EX and use it to query "vmm capabilities" on
module init.

Patches 4-5:
Check a feature bit in vmm capabilities, to take a new code path for mapping
stats and vp state pages. In this case, the stats and vp state pages must be
allocated by Linux, and a new hypercall HVCALL_MAP_VP_STATS_PAGE2 must be used
to map the stats page.

---
v3:
- Fix bug in patch 4, in mshv_partition_ioctl_create_vp() cleanup path
  [kernel test robot]
- Make hv_unmap_vp_state_page() use struct page to match hv_map_vp_state_page()
- Remove SELF == PARENT check which doesn't belong in patch 5 [Easwar]

v2:
https://lore.kernel.org/linux-hyperv/1757546089-2002-1-git-send-email-nunodasneves@linux.microsoft.com/T/#t
- Remove patch falling back to SELF page if PARENT mapping fails [Easwar]
  (To be included in a future series)
- Fix formatting of function definitions [Easwar]
  - Fix some wording in commit messages [Praveen]
    - Proceed with driver init even if getting vmm capabilities fails [Anirudh]

v1:
https://lore.kernel.org/linux-hyperv/1756428230-3599-1-git-send-email-nunodasneves@linux.microsoft.com/T/#t

---
Jinank Jain (2):
  mshv: Allocate vp state page for HVCALL_MAP_VP_STATE_PAGE on L1VH
  mshv: Introduce new hypercall to map stats page for L1VH partitions

Nuno Das Neves (1):
  mshv: Only map vp->vp_stats_pages if on root scheduler

Purna Pavan Chandra Aekkaladevi (2):
  mshv: Add the HVCALL_GET_PARTITION_PROPERTY_EX hypercall
  mshv: Get the vmm capabilities offered by the hypervisor

 drivers/hv/mshv_root.h         |  24 +++--
 drivers/hv/mshv_root_hv_call.c | 181 +++++++++++++++++++++++++++++++--
 drivers/hv/mshv_root_main.c    | 132 ++++++++++++++----------
 include/hyperv/hvgdk_mini.h    |   2 +
 include/hyperv/hvhdk.h         |  40 ++++++++
 include/hyperv/hvhdk_mini.h    |  33 ++++++
 6 files changed, 338 insertions(+), 74 deletions(-)

-- 
2.34.1

[PATCH v3 1/5] mshv: Only map vp->vp_stats_pages if on root scheduler

[Nuno Das Neves]

This mapping is only used for checking if the dispatch thread is
blocked. This is only relevant for the root scheduler, so check the
scheduler type to determine whether to map/unmap these pages, instead of
the current check, which is incorrect.

Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam <anirudh@anirudhrb.com>
Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
---
 drivers/hv/mshv_root_main.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index e3b2bd417c46..24df47726363 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -934,7 +934,11 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
 			goto unmap_register_page;
 	}
 
-	if (hv_parent_partition()) {
+	/*
+	 * This mapping of the stats page is for detecting if dispatch thread
+	 * is blocked - only relevant for root scheduler
+	 */
+	if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT) {
 		ret = mshv_vp_stats_map(partition->pt_id, args.vp_index,
 					stats_pages);
 		if (ret)
@@ -963,7 +967,7 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
 	if (mshv_partition_encrypted(partition) && is_ghcb_mapping_available())
 		vp->vp_ghcb_page = page_to_virt(ghcb_page);
 
-	if (hv_parent_partition())
+	if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
 		memcpy(vp->vp_stats_pages, stats_pages, sizeof(stats_pages));
 
 	/*
@@ -986,7 +990,7 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
 free_vp:
 	kfree(vp);
 unmap_stats_pages:
-	if (hv_parent_partition())
+	if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
 		mshv_vp_stats_unmap(partition->pt_id, args.vp_index);
 unmap_ghcb_page:
 	if (mshv_partition_encrypted(partition) && is_ghcb_mapping_available()) {
@@ -1740,7 +1744,7 @@ static void destroy_partition(struct mshv_partition *partition)
 			if (!vp)
 				continue;
 
-			if (hv_parent_partition())
+			if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
 				mshv_vp_stats_unmap(partition->pt_id, vp->vp_index);
 
 			if (vp->vp_register_page) {
-- 
2.34.1

Re: [PATCH v3 1/5] mshv: Only map vp->vp_stats_pages if on root scheduler

[Stanislav Kinsburskii]

On Tue, Sep 16, 2025 at 04:44:18PM -0700, Nuno Das Neves wrote:
> This mapping is only used for checking if the dispatch thread is
> blocked. This is only relevant for the root scheduler, so check the
> scheduler type to determine whether to map/unmap these pages, instead of
> the current check, which is incorrect.
> 
> Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
> Reviewed-by: Anirudh Rayabharam <anirudh@anirudhrb.com>
> Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
> Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
> Reviewed-by: Tianyu Lan <tiala@microsoft.com>
> ---
>  drivers/hv/mshv_root_main.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
> index e3b2bd417c46..24df47726363 100644
> --- a/drivers/hv/mshv_root_main.c
> +++ b/drivers/hv/mshv_root_main.c
> @@ -934,7 +934,11 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
>  			goto unmap_register_page;
>  	}
>  
> -	if (hv_parent_partition()) {
> +	/*
> +	 * This mapping of the stats page is for detecting if dispatch thread
> +	 * is blocked - only relevant for root scheduler
> +	 */
> +	if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT) {
>  		ret = mshv_vp_stats_map(partition->pt_id, args.vp_index,
>  					stats_pages);
>  		if (ret)
> @@ -963,7 +967,7 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
>  	if (mshv_partition_encrypted(partition) && is_ghcb_mapping_available())
>  		vp->vp_ghcb_page = page_to_virt(ghcb_page);
>  
> -	if (hv_parent_partition())
> +	if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
>  		memcpy(vp->vp_stats_pages, stats_pages, sizeof(stats_pages));
>  
>  	/*
> @@ -986,7 +990,7 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
>  free_vp:
>  	kfree(vp);
>  unmap_stats_pages:
> -	if (hv_parent_partition())
> +	if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
>  		mshv_vp_stats_unmap(partition->pt_id, args.vp_index);
>  unmap_ghcb_page:
>  	if (mshv_partition_encrypted(partition) && is_ghcb_mapping_available()) {
> @@ -1740,7 +1744,7 @@ static void destroy_partition(struct mshv_partition *partition)
>  			if (!vp)
>  				continue;
>  
> -			if (hv_parent_partition())
> +			if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
>  				mshv_vp_stats_unmap(partition->pt_id, vp->vp_index);
>  
>  			if (vp->vp_register_page) {

Acked-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>

> -- 
> 2.34.1
> 

[PATCH v3 2/5] mshv: Add the HVCALL_GET_PARTITION_PROPERTY_EX hypercall

[Nuno Das Neves]

From: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>

This hypercall can be used to fetch extended properties of a
partition. Extended properties are properties with values larger than
a u64. Some of these also need additional input arguments.

Add helper function for using the hypercall in the mshv_root driver.

Signed-off-by: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam <anirudh@anirudhrb.com>
Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
---
 drivers/hv/mshv_root.h         |  2 ++
 drivers/hv/mshv_root_hv_call.c | 31 ++++++++++++++++++++++++++
 include/hyperv/hvgdk_mini.h    |  1 +
 include/hyperv/hvhdk.h         | 40 ++++++++++++++++++++++++++++++++++
 include/hyperv/hvhdk_mini.h    | 26 ++++++++++++++++++++++
 5 files changed, 100 insertions(+)

diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
index e3931b0f1269..4aeb03bea6b6 100644
--- a/drivers/hv/mshv_root.h
+++ b/drivers/hv/mshv_root.h
@@ -303,6 +303,8 @@ int hv_call_unmap_stat_page(enum hv_stats_object_type type,
 int hv_call_modify_spa_host_access(u64 partition_id, struct page **pages,
 				   u64 page_struct_count, u32 host_access,
 				   u32 flags, u8 acquire);
+int hv_call_get_partition_property_ex(u64 partition_id, u64 property_code, u64 arg,
+				      void *property_value, size_t property_value_sz);
 
 extern struct mshv_root mshv_root;
 extern enum hv_scheduler_type hv_scheduler_type;
diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c
index c9c274f29c3c..3fd3cce23f69 100644
--- a/drivers/hv/mshv_root_hv_call.c
+++ b/drivers/hv/mshv_root_hv_call.c
@@ -590,6 +590,37 @@ int hv_call_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
 	return hv_result_to_errno(status);
 }
 
+int hv_call_get_partition_property_ex(u64 partition_id, u64 property_code,
+				      u64 arg, void *property_value,
+				      size_t property_value_sz)
+{
+	u64 status;
+	unsigned long flags;
+	struct hv_input_get_partition_property_ex *input;
+	struct hv_output_get_partition_property_ex *output;
+
+	local_irq_save(flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+	memset(input, 0, sizeof(*input));
+	input->partition_id = partition_id;
+	input->property_code = property_code;
+	input->arg = arg;
+	status = hv_do_hypercall(HVCALL_GET_PARTITION_PROPERTY_EX, input, output);
+
+	if (!hv_result_success(status)) {
+		hv_status_debug(status, "\n");
+		local_irq_restore(flags);
+		return hv_result_to_errno(status);
+	}
+	memcpy(property_value, &output->property_value, property_value_sz);
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+
 int
 hv_call_clear_virtual_interrupt(u64 partition_id)
 {
diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
index 1be7f6a02304..ff4325fb623a 100644
--- a/include/hyperv/hvgdk_mini.h
+++ b/include/hyperv/hvgdk_mini.h
@@ -490,6 +490,7 @@ union hv_vp_assist_msr_contents {	 /* HV_REGISTER_VP_ASSIST_PAGE */
 #define HVCALL_GET_VP_STATE				0x00e3
 #define HVCALL_SET_VP_STATE				0x00e4
 #define HVCALL_GET_VP_CPUID_VALUES			0x00f4
+#define HVCALL_GET_PARTITION_PROPERTY_EX		0x0101
 #define HVCALL_MMIO_READ				0x0106
 #define HVCALL_MMIO_WRITE				0x0107
 
diff --git a/include/hyperv/hvhdk.h b/include/hyperv/hvhdk.h
index b4067ada02cf..b91358b9c929 100644
--- a/include/hyperv/hvhdk.h
+++ b/include/hyperv/hvhdk.h
@@ -376,6 +376,46 @@ struct hv_input_set_partition_property {
 	u64 property_value;
 } __packed;
 
+union hv_partition_property_arg {
+	u64 as_uint64;
+	struct {
+		union {
+			u32 arg;
+			u32 vp_index;
+		};
+		u16 reserved0;
+		u8 reserved1;
+		u8 object_type;
+	};
+} __packed;
+
+struct hv_input_get_partition_property_ex {
+	u64 partition_id;
+	u32 property_code; /* enum hv_partition_property_code */
+	u32 padding;
+	union {
+		union hv_partition_property_arg arg_data;
+		u64 arg;
+	};
+} __packed;
+
+/*
+ * NOTE: Should use hv_input_set_partition_property_ex_header to compute this
+ * size, but hv_input_get_partition_property_ex is identical so it suffices
+ */
+#define HV_PARTITION_PROPERTY_EX_MAX_VAR_SIZE \
+	(HV_HYP_PAGE_SIZE - sizeof(struct hv_input_get_partition_property_ex))
+
+union hv_partition_property_ex {
+	u8 buffer[HV_PARTITION_PROPERTY_EX_MAX_VAR_SIZE];
+	struct hv_partition_property_vmm_capabilities vmm_capabilities;
+	/* More fields to be filled in when needed */
+} __packed;
+
+struct hv_output_get_partition_property_ex {
+	union hv_partition_property_ex property_value;
+} __packed;
+
 enum hv_vp_state_page_type {
 	HV_VP_STATE_PAGE_REGISTERS = 0,
 	HV_VP_STATE_PAGE_INTERCEPT_MESSAGE = 1,
diff --git a/include/hyperv/hvhdk_mini.h b/include/hyperv/hvhdk_mini.h
index 858f6a3925b3..bf2ce27dfcc5 100644
--- a/include/hyperv/hvhdk_mini.h
+++ b/include/hyperv/hvhdk_mini.h
@@ -96,8 +96,34 @@ enum hv_partition_property_code {
 	HV_PARTITION_PROPERTY_XSAVE_STATES                      = 0x00060007,
 	HV_PARTITION_PROPERTY_MAX_XSAVE_DATA_SIZE		= 0x00060008,
 	HV_PARTITION_PROPERTY_PROCESSOR_CLOCK_FREQUENCY		= 0x00060009,
+
+	/* Extended properties with larger property values */
+	HV_PARTITION_PROPERTY_VMM_CAPABILITIES			= 0x00090007,
 };
 
+#define HV_PARTITION_VMM_CAPABILITIES_BANK_COUNT		1
+#define HV_PARTITION_VMM_CAPABILITIES_RESERVED_BITFIELD_COUNT	59
+
+struct hv_partition_property_vmm_capabilities {
+	u16 bank_count;
+	u16 reserved[3];
+	union {
+		u64 as_uint64[HV_PARTITION_VMM_CAPABILITIES_BANK_COUNT];
+		struct {
+			u64 map_gpa_preserve_adjustable: 1;
+			u64 vmm_can_provide_overlay_gpfn: 1;
+			u64 vp_affinity_property: 1;
+#if IS_ENABLED(CONFIG_ARM64)
+			u64 vmm_can_provide_gic_overlay_locations: 1;
+#else
+			u64 reservedbit3: 1;
+#endif
+			u64 assignable_synthetic_proc_features: 1;
+			u64 reserved0: HV_PARTITION_VMM_CAPABILITIES_RESERVED_BITFIELD_COUNT;
+		} __packed;
+	};
+} __packed;
+
 enum hv_snp_status {
 	HV_SNP_STATUS_NONE = 0,
 	HV_SNP_STATUS_AVAILABLE = 1,
-- 
2.34.1

Re: [PATCH v3 2/5] mshv: Add the HVCALL_GET_PARTITION_PROPERTY_EX hypercall

[Stanislav Kinsburskii]

On Tue, Sep 16, 2025 at 04:44:19PM -0700, Nuno Das Neves wrote:

<snip>

> diff --git a/include/hyperv/hvhdk.h b/include/hyperv/hvhdk.h
> index b4067ada02cf..b91358b9c929 100644
> --- a/include/hyperv/hvhdk.h
> +++ b/include/hyperv/hvhdk.h
> @@ -376,6 +376,46 @@ struct hv_input_set_partition_property {
>  	u64 property_value;
>  } __packed;
>  
> +union hv_partition_property_arg {
> +	u64 as_uint64;
> +	struct {
> +		union {
> +			u32 arg;
> +			u32 vp_index;
> +		};
> +		u16 reserved0;
> +		u8 reserved1;
> +		u8 object_type;
> +	};
> +} __packed;

Shouldn't the struct be "packed" instead?

> +
> +struct hv_input_get_partition_property_ex {
> +	u64 partition_id;
> +	u32 property_code; /* enum hv_partition_property_code */
> +	u32 padding;
> +	union {
> +		union hv_partition_property_arg arg_data;
> +		u64 arg;
> +	};
> +} __packed;
> +
> +/*
> + * NOTE: Should use hv_input_set_partition_property_ex_header to compute this
> + * size, but hv_input_get_partition_property_ex is identical so it suffices
> + */
> +#define HV_PARTITION_PROPERTY_EX_MAX_VAR_SIZE \
> +	(HV_HYP_PAGE_SIZE - sizeof(struct hv_input_get_partition_property_ex))
> +
> +union hv_partition_property_ex {
> +	u8 buffer[HV_PARTITION_PROPERTY_EX_MAX_VAR_SIZE];
> +	struct hv_partition_property_vmm_capabilities vmm_capabilities;
> +	/* More fields to be filled in when needed */
> +} __packed;

Packing a union is redundant.

Thanks,
Stanislav

Re: [PATCH v3 2/5] mshv: Add the HVCALL_GET_PARTITION_PROPERTY_EX hypercall

[Nuno Das Neves]

On 9/18/2025 11:43 AM, Stanislav Kinsburskii wrote:
> On Tue, Sep 16, 2025 at 04:44:19PM -0700, Nuno Das Neves wrote:
> 
> <snip>
> 
>> diff --git a/include/hyperv/hvhdk.h b/include/hyperv/hvhdk.h
>> index b4067ada02cf..b91358b9c929 100644
>> --- a/include/hyperv/hvhdk.h
>> +++ b/include/hyperv/hvhdk.h
>> @@ -376,6 +376,46 @@ struct hv_input_set_partition_property {
>>  	u64 property_value;
>>  } __packed;
>>  
>> +union hv_partition_property_arg {
>> +	u64 as_uint64;
>> +	struct {
>> +		union {
>> +			u32 arg;
>> +			u32 vp_index;
>> +		};
>> +		u16 reserved0;
>> +		u8 reserved1;
>> +		u8 object_type;
>> +	};
>> +} __packed;
> 
> Shouldn't the struct be "packed" instead?
> 
Indeed, I'll fix it, thanks.

>> +
>> +struct hv_input_get_partition_property_ex {
>> +	u64 partition_id;
>> +	u32 property_code; /* enum hv_partition_property_code */
>> +	u32 padding;
>> +	union {
>> +		union hv_partition_property_arg arg_data;
>> +		u64 arg;
>> +	};
>> +} __packed;
>> +
>> +/*
>> + * NOTE: Should use hv_input_set_partition_property_ex_header to compute this
>> + * size, but hv_input_get_partition_property_ex is identical so it suffices
>> + */
>> +#define HV_PARTITION_PROPERTY_EX_MAX_VAR_SIZE \
>> +	(HV_HYP_PAGE_SIZE - sizeof(struct hv_input_get_partition_property_ex))
>> +
>> +union hv_partition_property_ex {
>> +	u8 buffer[HV_PARTITION_PROPERTY_EX_MAX_VAR_SIZE];
>> +	struct hv_partition_property_vmm_capabilities vmm_capabilities;
>> +	/* More fields to be filled in when needed */
>> +} __packed;
> 
> Packing a union is redundant.
> 
> Thanks,
> Stanislav

[PATCH v3 3/5] mshv: Get the vmm capabilities offered by the hypervisor

[Nuno Das Neves]

From: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>

Some hypervisor APIs are gated by feature bits in the
"vmm capabilities" partition property. Store the capabilities on
mshv_root module init, using HVCALL_GET_PARTITION_PROPERTY_EX.

This is not supported on all hypervisors. In that case, just set the
capabilities to 0 and proceed as normal.

Signed-off-by: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
---
 drivers/hv/mshv_root.h      |  1 +
 drivers/hv/mshv_root_main.c | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
index 4aeb03bea6b6..0cb1e2589fe1 100644
--- a/drivers/hv/mshv_root.h
+++ b/drivers/hv/mshv_root.h
@@ -178,6 +178,7 @@ struct mshv_root {
 	struct hv_synic_pages __percpu *synic_pages;
 	spinlock_t pt_ht_lock;
 	DECLARE_HASHTABLE(pt_htable, MSHV_PARTITIONS_HASH_BITS);
+	struct hv_partition_property_vmm_capabilities vmm_caps;
 };
 
 /*
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index 24df47726363..f7738cefbdf3 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -2201,6 +2201,26 @@ static int __init mshv_root_partition_init(struct device *dev)
 	return err;
 }
 
+static void mshv_init_vmm_caps(struct device *dev)
+{
+	int ret;
+
+	memset(&mshv_root.vmm_caps, 0, sizeof(mshv_root.vmm_caps));
+	ret = hv_call_get_partition_property_ex(HV_PARTITION_ID_SELF,
+						HV_PARTITION_PROPERTY_VMM_CAPABILITIES,
+						0, &mshv_root.vmm_caps,
+						sizeof(mshv_root.vmm_caps));
+
+	/*
+	 * HVCALL_GET_PARTITION_PROPERTY_EX or HV_PARTITION_PROPERTY_VMM_CAPABILITIES
+	 * may not be supported. Leave them as 0 in that case.
+	 */
+	if (ret)
+		dev_warn(dev, "Unable to get VMM capabilities\n");
+
+	dev_dbg(dev, "vmm_caps=0x%llx\n", mshv_root.vmm_caps.as_uint64[0]);
+}
+
 static int __init mshv_parent_partition_init(void)
 {
 	int ret;
@@ -2253,6 +2273,8 @@ static int __init mshv_parent_partition_init(void)
 	if (ret)
 		goto remove_cpu_state;
 
+	mshv_init_vmm_caps(dev);
+
 	ret = mshv_irqfd_wq_init();
 	if (ret)
 		goto exit_partition;
-- 
2.34.1

Re: [PATCH v3 3/5] mshv: Get the vmm capabilities offered by the hypervisor

[Stanislav Kinsburskii]

On Tue, Sep 16, 2025 at 04:44:20PM -0700, Nuno Das Neves wrote:
> From: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>
> 
> Some hypervisor APIs are gated by feature bits in the
> "vmm capabilities" partition property. Store the capabilities on
> mshv_root module init, using HVCALL_GET_PARTITION_PROPERTY_EX.
> 
> This is not supported on all hypervisors. In that case, just set the
> capabilities to 0 and proceed as normal.
> 
> Signed-off-by: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>
> Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
> Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
> Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
> Reviewed-by: Tianyu Lan <tiala@microsoft.com>
> ---
>  drivers/hv/mshv_root.h      |  1 +
>  drivers/hv/mshv_root_main.c | 22 ++++++++++++++++++++++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
> index 4aeb03bea6b6..0cb1e2589fe1 100644
> --- a/drivers/hv/mshv_root.h
> +++ b/drivers/hv/mshv_root.h
> @@ -178,6 +178,7 @@ struct mshv_root {
>  	struct hv_synic_pages __percpu *synic_pages;
>  	spinlock_t pt_ht_lock;
>  	DECLARE_HASHTABLE(pt_htable, MSHV_PARTITIONS_HASH_BITS);
> +	struct hv_partition_property_vmm_capabilities vmm_caps;
>  };
>  
>  /*
> diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
> index 24df47726363..f7738cefbdf3 100644
> --- a/drivers/hv/mshv_root_main.c
> +++ b/drivers/hv/mshv_root_main.c
> @@ -2201,6 +2201,26 @@ static int __init mshv_root_partition_init(struct device *dev)
>  	return err;
>  }
>  
> +static void mshv_init_vmm_caps(struct device *dev)
> +{
> +	int ret;

nit: this is void function so ret looks redundant.

> +
> +	memset(&mshv_root.vmm_caps, 0, sizeof(mshv_root.vmm_caps));

Zeroying is redundant as mshv_root is a statci variable.

> +	ret = hv_call_get_partition_property_ex(HV_PARTITION_ID_SELF,
> +						HV_PARTITION_PROPERTY_VMM_CAPABILITIES,
> +						0, &mshv_root.vmm_caps,

Also, we align "slow" hypercalls by PAGE_SIZE. Why is it fine to not do
it here?

Thanks,
Stanislav

> +						sizeof(mshv_root.vmm_caps));
> +
> +	/*
> +	 * HVCALL_GET_PARTITION_PROPERTY_EX or HV_PARTITION_PROPERTY_VMM_CAPABILITIES
> +	 * may not be supported. Leave them as 0 in that case.
> +	 */
> +	if (ret)
> +		dev_warn(dev, "Unable to get VMM capabilities\n");
> +
> +	dev_dbg(dev, "vmm_caps=0x%llx\n", mshv_root.vmm_caps.as_uint64[0]);
> +}
> +
>  static int __init mshv_parent_partition_init(void)
>  {
>  	int ret;
> @@ -2253,6 +2273,8 @@ static int __init mshv_parent_partition_init(void)
>  	if (ret)
>  		goto remove_cpu_state;
>  
> +	mshv_init_vmm_caps(dev);
> +
>  	ret = mshv_irqfd_wq_init();
>  	if (ret)
>  		goto exit_partition;
> -- 
> 2.34.1
> 

Re: [PATCH v3 3/5] mshv: Get the vmm capabilities offered by the hypervisor

[Nuno Das Neves]

On 9/18/2025 11:50 AM, Stanislav Kinsburskii wrote:
> On Tue, Sep 16, 2025 at 04:44:20PM -0700, Nuno Das Neves wrote:
>> From: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>
>>
>> Some hypervisor APIs are gated by feature bits in the
>> "vmm capabilities" partition property. Store the capabilities on
>> mshv_root module init, using HVCALL_GET_PARTITION_PROPERTY_EX.
>>
>> This is not supported on all hypervisors. In that case, just set the
>> capabilities to 0 and proceed as normal.
>>
>> Signed-off-by: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>
>> Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
>> Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
>> Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
>> Reviewed-by: Tianyu Lan <tiala@microsoft.com>
>> ---
>>  drivers/hv/mshv_root.h      |  1 +
>>  drivers/hv/mshv_root_main.c | 22 ++++++++++++++++++++++
>>  2 files changed, 23 insertions(+)
>>
>> diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
>> index 4aeb03bea6b6..0cb1e2589fe1 100644
>> --- a/drivers/hv/mshv_root.h
>> +++ b/drivers/hv/mshv_root.h
>> @@ -178,6 +178,7 @@ struct mshv_root {
>>  	struct hv_synic_pages __percpu *synic_pages;
>>  	spinlock_t pt_ht_lock;
>>  	DECLARE_HASHTABLE(pt_htable, MSHV_PARTITIONS_HASH_BITS);
>> +	struct hv_partition_property_vmm_capabilities vmm_caps;
>>  };
>>  
>>  /*
>> diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
>> index 24df47726363..f7738cefbdf3 100644
>> --- a/drivers/hv/mshv_root_main.c
>> +++ b/drivers/hv/mshv_root_main.c
>> @@ -2201,6 +2201,26 @@ static int __init mshv_root_partition_init(struct device *dev)
>>  	return err;
>>  }
>>  
>> +static void mshv_init_vmm_caps(struct device *dev)
>> +{
>> +	int ret;
> 
> nit: this is void function so ret looks redundant.
> 

True, it's not needed.

>> +
>> +	memset(&mshv_root.vmm_caps, 0, sizeof(mshv_root.vmm_caps));
> 
> Zeroying is redundant as mshv_root is a statci variable.
> 

Good point.

>> +	ret = hv_call_get_partition_property_ex(HV_PARTITION_ID_SELF,
>> +						HV_PARTITION_PROPERTY_VMM_CAPABILITIES,
>> +						0, &mshv_root.vmm_caps,
> 
> Also, we align "slow" hypercalls by PAGE_SIZE. Why is it fine to not do
> it here?
> 

I guess you're referring to the output argument of the hypercall?

Check the previous patch to see how hv_call_get_partition_property_ex()
is implemented. It uses the per-cpu input/output args as normal, which
are HV_HYP_PAGE_SIZE in size, and page-aligned.

> Thanks,
> Stanislav
> 
>> +						sizeof(mshv_root.vmm_caps));
>> +
>> +	/*
>> +	 * HVCALL_GET_PARTITION_PROPERTY_EX or HV_PARTITION_PROPERTY_VMM_CAPABILITIES
>> +	 * may not be supported. Leave them as 0 in that case.
>> +	 */
>> +	if (ret)
>> +		dev_warn(dev, "Unable to get VMM capabilities\n");
>> +
>> +	dev_dbg(dev, "vmm_caps=0x%llx\n", mshv_root.vmm_caps.as_uint64[0]);
>> +}
>> +
>>  static int __init mshv_parent_partition_init(void)
>>  {
>>  	int ret;
>> @@ -2253,6 +2273,8 @@ static int __init mshv_parent_partition_init(void)
>>  	if (ret)
>>  		goto remove_cpu_state;
>>  
>> +	mshv_init_vmm_caps(dev);
>> +
>>  	ret = mshv_irqfd_wq_init();
>>  	if (ret)
>>  		goto exit_partition;
>> -- 
>> 2.34.1
>>

[PATCH v3 4/5] mshv: Allocate vp state page for HVCALL_MAP_VP_STATE_PAGE on L1VH

[Nuno Das Neves]

From: Jinank Jain <jinankjain@linux.microsoft.com>

Introduce mshv_use_overlay_gpfn() to check if a page needs to be
allocated and passed to the hypervisor to map VP state pages. This is
only needed on L1VH, and only on some (newer) versions of the
hypervisor, hence the need to check vmm_capabilities.

Introduce functions hv_map/unmap_vp_state_page() to handle the
allocation and freeing.

Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
---
 drivers/hv/mshv_root.h         | 11 ++---
 drivers/hv/mshv_root_hv_call.c | 61 ++++++++++++++++++++++++---
 drivers/hv/mshv_root_main.c    | 76 +++++++++++++++++-----------------
 3 files changed, 98 insertions(+), 50 deletions(-)

diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
index 0cb1e2589fe1..dbe2d1d0b22f 100644
--- a/drivers/hv/mshv_root.h
+++ b/drivers/hv/mshv_root.h
@@ -279,11 +279,12 @@ int hv_call_set_vp_state(u32 vp_index, u64 partition_id,
 			 /* Choose between pages and bytes */
 			 struct hv_vp_state_data state_data, u64 page_count,
 			 struct page **pages, u32 num_bytes, u8 *bytes);
-int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
-			      union hv_input_vtl input_vtl,
-			      struct page **state_page);
-int hv_call_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
-				union hv_input_vtl input_vtl);
+int hv_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+			 union hv_input_vtl input_vtl,
+			 struct page **state_page);
+int hv_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+			   struct page *state_page,
+			   union hv_input_vtl input_vtl);
 int hv_call_create_port(u64 port_partition_id, union hv_port_id port_id,
 			u64 connection_partition_id, struct hv_port_info *port_info,
 			u8 port_vtl, u8 min_connection_vtl, int node);
diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c
index 3fd3cce23f69..98c6278ff151 100644
--- a/drivers/hv/mshv_root_hv_call.c
+++ b/drivers/hv/mshv_root_hv_call.c
@@ -526,9 +526,9 @@ int hv_call_set_vp_state(u32 vp_index, u64 partition_id,
 	return ret;
 }
 
-int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
-			      union hv_input_vtl input_vtl,
-			      struct page **state_page)
+static int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+				     union hv_input_vtl input_vtl,
+				     struct page **state_page)
 {
 	struct hv_input_map_vp_state_page *input;
 	struct hv_output_map_vp_state_page *output;
@@ -547,7 +547,14 @@ int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
 		input->type = type;
 		input->input_vtl = input_vtl;
 
-		status = hv_do_hypercall(HVCALL_MAP_VP_STATE_PAGE, input, output);
+		if (*state_page) {
+			input->flags.map_location_provided = 1;
+			input->requested_map_location =
+				page_to_pfn(*state_page);
+		}
+
+		status = hv_do_hypercall(HVCALL_MAP_VP_STATE_PAGE, input,
+					 output);
 
 		if (hv_result(status) != HV_STATUS_INSUFFICIENT_MEMORY) {
 			if (hv_result_success(status))
@@ -565,8 +572,39 @@ int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
 	return ret;
 }
 
-int hv_call_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
-				union hv_input_vtl input_vtl)
+static bool mshv_use_overlay_gpfn(void)
+{
+	return hv_l1vh_partition() &&
+	       mshv_root.vmm_caps.vmm_can_provide_overlay_gpfn;
+}
+
+int hv_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+			 union hv_input_vtl input_vtl,
+			 struct page **state_page)
+{
+	int ret = 0;
+	struct page *allocated_page = NULL;
+
+	if (mshv_use_overlay_gpfn()) {
+		allocated_page = alloc_page(GFP_KERNEL);
+		if (!allocated_page)
+			return -ENOMEM;
+		*state_page = allocated_page;
+	} else {
+		*state_page = NULL;
+	}
+
+	ret = hv_call_map_vp_state_page(partition_id, vp_index, type, input_vtl,
+					state_page);
+
+	if (ret && allocated_page)
+		__free_page(allocated_page);
+
+	return ret;
+}
+
+static int hv_call_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+				       union hv_input_vtl input_vtl)
 {
 	unsigned long flags;
 	u64 status;
@@ -590,6 +628,17 @@ int hv_call_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
 	return hv_result_to_errno(status);
 }
 
+int hv_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+			   struct page *state_page, union hv_input_vtl input_vtl)
+{
+	int ret = hv_call_unmap_vp_state_page(partition_id, vp_index, type, input_vtl);
+
+	if (mshv_use_overlay_gpfn() && state_page)
+		__free_page(state_page);
+
+	return ret;
+}
+
 int hv_call_get_partition_property_ex(u64 partition_id, u64 property_code,
 				      u64 arg, void *property_value,
 				      size_t property_value_sz)
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index f7738cefbdf3..52f69eace9b9 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -890,7 +890,7 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
 {
 	struct mshv_create_vp args;
 	struct mshv_vp *vp;
-	struct page *intercept_message_page, *register_page, *ghcb_page;
+	struct page *intercept_msg_page, *register_page, *ghcb_page;
 	void *stats_pages[2];
 	long ret;
 
@@ -908,28 +908,25 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
 	if (ret)
 		return ret;
 
-	ret = hv_call_map_vp_state_page(partition->pt_id, args.vp_index,
-					HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
-					input_vtl_zero,
-					&intercept_message_page);
+	ret = hv_map_vp_state_page(partition->pt_id, args.vp_index,
+				   HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
+				   input_vtl_zero, &intercept_msg_page);
 	if (ret)
 		goto destroy_vp;
 
 	if (!mshv_partition_encrypted(partition)) {
-		ret = hv_call_map_vp_state_page(partition->pt_id, args.vp_index,
-						HV_VP_STATE_PAGE_REGISTERS,
-						input_vtl_zero,
-						&register_page);
+		ret = hv_map_vp_state_page(partition->pt_id, args.vp_index,
+					   HV_VP_STATE_PAGE_REGISTERS,
+					   input_vtl_zero, &register_page);
 		if (ret)
 			goto unmap_intercept_message_page;
 	}
 
 	if (mshv_partition_encrypted(partition) &&
 	    is_ghcb_mapping_available()) {
-		ret = hv_call_map_vp_state_page(partition->pt_id, args.vp_index,
-						HV_VP_STATE_PAGE_GHCB,
-						input_vtl_normal,
-						&ghcb_page);
+		ret = hv_map_vp_state_page(partition->pt_id, args.vp_index,
+					   HV_VP_STATE_PAGE_GHCB,
+					   input_vtl_normal, &ghcb_page);
 		if (ret)
 			goto unmap_register_page;
 	}
@@ -960,7 +957,7 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
 	atomic64_set(&vp->run.vp_signaled_count, 0);
 
 	vp->vp_index = args.vp_index;
-	vp->vp_intercept_msg_page = page_to_virt(intercept_message_page);
+	vp->vp_intercept_msg_page = page_to_virt(intercept_msg_page);
 	if (!mshv_partition_encrypted(partition))
 		vp->vp_register_page = page_to_virt(register_page);
 
@@ -993,21 +990,19 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
 	if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
 		mshv_vp_stats_unmap(partition->pt_id, args.vp_index);
 unmap_ghcb_page:
-	if (mshv_partition_encrypted(partition) && is_ghcb_mapping_available()) {
-		hv_call_unmap_vp_state_page(partition->pt_id, args.vp_index,
-					    HV_VP_STATE_PAGE_GHCB,
-					    input_vtl_normal);
-	}
+	if (mshv_partition_encrypted(partition) && is_ghcb_mapping_available())
+		hv_unmap_vp_state_page(partition->pt_id, args.vp_index,
+				       HV_VP_STATE_PAGE_GHCB, ghcb_page,
+				       input_vtl_normal);
 unmap_register_page:
-	if (!mshv_partition_encrypted(partition)) {
-		hv_call_unmap_vp_state_page(partition->pt_id, args.vp_index,
-					    HV_VP_STATE_PAGE_REGISTERS,
-					    input_vtl_zero);
-	}
+	if (!mshv_partition_encrypted(partition))
+		hv_unmap_vp_state_page(partition->pt_id, args.vp_index,
+				       HV_VP_STATE_PAGE_REGISTERS,
+				       register_page, input_vtl_zero);
 unmap_intercept_message_page:
-	hv_call_unmap_vp_state_page(partition->pt_id, args.vp_index,
-				    HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
-				    input_vtl_zero);
+	hv_unmap_vp_state_page(partition->pt_id, args.vp_index,
+			       HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
+			       intercept_msg_page, input_vtl_zero);
 destroy_vp:
 	hv_call_delete_vp(partition->pt_id, args.vp_index);
 	return ret;
@@ -1748,24 +1743,27 @@ static void destroy_partition(struct mshv_partition *partition)
 				mshv_vp_stats_unmap(partition->pt_id, vp->vp_index);
 
 			if (vp->vp_register_page) {
-				(void)hv_call_unmap_vp_state_page(partition->pt_id,
-								  vp->vp_index,
-								  HV_VP_STATE_PAGE_REGISTERS,
-								  input_vtl_zero);
+				(void)hv_unmap_vp_state_page(partition->pt_id,
+							     vp->vp_index,
+							     HV_VP_STATE_PAGE_REGISTERS,
+							     virt_to_page(vp->vp_register_page),
+							     input_vtl_zero);
 				vp->vp_register_page = NULL;
 			}
 
-			(void)hv_call_unmap_vp_state_page(partition->pt_id,
-							  vp->vp_index,
-							  HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
-							  input_vtl_zero);
+			(void)hv_unmap_vp_state_page(partition->pt_id,
+						     vp->vp_index,
+						     HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
+						     virt_to_page(vp->vp_intercept_msg_page),
+						     input_vtl_zero);
 			vp->vp_intercept_msg_page = NULL;
 
 			if (vp->vp_ghcb_page) {
-				(void)hv_call_unmap_vp_state_page(partition->pt_id,
-								  vp->vp_index,
-								  HV_VP_STATE_PAGE_GHCB,
-								  input_vtl_normal);
+				(void)hv_unmap_vp_state_page(partition->pt_id,
+							     vp->vp_index,
+							     HV_VP_STATE_PAGE_GHCB,
+							     virt_to_page(vp->vp_ghcb_page),
+							     input_vtl_normal);
 				vp->vp_ghcb_page = NULL;
 			}
 
-- 
2.34.1

Re: [PATCH v3 4/5] mshv: Allocate vp state page for HVCALL_MAP_VP_STATE_PAGE on L1VH

[Stanislav Kinsburskii]

On Tue, Sep 16, 2025 at 04:44:21PM -0700, Nuno Das Neves wrote:
> From: Jinank Jain <jinankjain@linux.microsoft.com>
> 

Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>

> Introduce mshv_use_overlay_gpfn() to check if a page needs to be
> allocated and passed to the hypervisor to map VP state pages. This is
> only needed on L1VH, and only on some (newer) versions of the
> hypervisor, hence the need to check vmm_capabilities.
> 
> Introduce functions hv_map/unmap_vp_state_page() to handle the
> allocation and freeing.
> 
> Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
> Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
> Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
> Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
> ---
>  drivers/hv/mshv_root.h         | 11 ++---
>  drivers/hv/mshv_root_hv_call.c | 61 ++++++++++++++++++++++++---
>  drivers/hv/mshv_root_main.c    | 76 +++++++++++++++++-----------------
>  3 files changed, 98 insertions(+), 50 deletions(-)
> 
> diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
> index 0cb1e2589fe1..dbe2d1d0b22f 100644
> --- a/drivers/hv/mshv_root.h
> +++ b/drivers/hv/mshv_root.h
> @@ -279,11 +279,12 @@ int hv_call_set_vp_state(u32 vp_index, u64 partition_id,
>  			 /* Choose between pages and bytes */
>  			 struct hv_vp_state_data state_data, u64 page_count,
>  			 struct page **pages, u32 num_bytes, u8 *bytes);
> -int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
> -			      union hv_input_vtl input_vtl,
> -			      struct page **state_page);
> -int hv_call_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
> -				union hv_input_vtl input_vtl);
> +int hv_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
> +			 union hv_input_vtl input_vtl,
> +			 struct page **state_page);
> +int hv_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
> +			   struct page *state_page,
> +			   union hv_input_vtl input_vtl);
>  int hv_call_create_port(u64 port_partition_id, union hv_port_id port_id,
>  			u64 connection_partition_id, struct hv_port_info *port_info,
>  			u8 port_vtl, u8 min_connection_vtl, int node);
> diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c
> index 3fd3cce23f69..98c6278ff151 100644
> --- a/drivers/hv/mshv_root_hv_call.c
> +++ b/drivers/hv/mshv_root_hv_call.c
> @@ -526,9 +526,9 @@ int hv_call_set_vp_state(u32 vp_index, u64 partition_id,
>  	return ret;
>  }
>  
> -int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
> -			      union hv_input_vtl input_vtl,
> -			      struct page **state_page)
> +static int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
> +				     union hv_input_vtl input_vtl,
> +				     struct page **state_page)
>  {
>  	struct hv_input_map_vp_state_page *input;
>  	struct hv_output_map_vp_state_page *output;
> @@ -547,7 +547,14 @@ int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
>  		input->type = type;
>  		input->input_vtl = input_vtl;
>  
> -		status = hv_do_hypercall(HVCALL_MAP_VP_STATE_PAGE, input, output);
> +		if (*state_page) {
> +			input->flags.map_location_provided = 1;
> +			input->requested_map_location =
> +				page_to_pfn(*state_page);
> +		}
> +
> +		status = hv_do_hypercall(HVCALL_MAP_VP_STATE_PAGE, input,
> +					 output);
>  
>  		if (hv_result(status) != HV_STATUS_INSUFFICIENT_MEMORY) {
>  			if (hv_result_success(status))
> @@ -565,8 +572,39 @@ int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
>  	return ret;
>  }
>  
> -int hv_call_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
> -				union hv_input_vtl input_vtl)
> +static bool mshv_use_overlay_gpfn(void)
> +{
> +	return hv_l1vh_partition() &&
> +	       mshv_root.vmm_caps.vmm_can_provide_overlay_gpfn;
> +}
> +
> +int hv_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
> +			 union hv_input_vtl input_vtl,
> +			 struct page **state_page)
> +{
> +	int ret = 0;
> +	struct page *allocated_page = NULL;
> +
> +	if (mshv_use_overlay_gpfn()) {
> +		allocated_page = alloc_page(GFP_KERNEL);
> +		if (!allocated_page)
> +			return -ENOMEM;
> +		*state_page = allocated_page;
> +	} else {
> +		*state_page = NULL;
> +	}
> +
> +	ret = hv_call_map_vp_state_page(partition_id, vp_index, type, input_vtl,
> +					state_page);
> +
> +	if (ret && allocated_page)
> +		__free_page(allocated_page);
> +
> +	return ret;
> +}
> +
> +static int hv_call_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
> +				       union hv_input_vtl input_vtl)
>  {
>  	unsigned long flags;
>  	u64 status;
> @@ -590,6 +628,17 @@ int hv_call_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
>  	return hv_result_to_errno(status);
>  }
>  
> +int hv_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
> +			   struct page *state_page, union hv_input_vtl input_vtl)
> +{
> +	int ret = hv_call_unmap_vp_state_page(partition_id, vp_index, type, input_vtl);
> +
> +	if (mshv_use_overlay_gpfn() && state_page)
> +		__free_page(state_page);
> +
> +	return ret;
> +}
> +
>  int hv_call_get_partition_property_ex(u64 partition_id, u64 property_code,
>  				      u64 arg, void *property_value,
>  				      size_t property_value_sz)
> diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
> index f7738cefbdf3..52f69eace9b9 100644
> --- a/drivers/hv/mshv_root_main.c
> +++ b/drivers/hv/mshv_root_main.c
> @@ -890,7 +890,7 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
>  {
>  	struct mshv_create_vp args;
>  	struct mshv_vp *vp;
> -	struct page *intercept_message_page, *register_page, *ghcb_page;
> +	struct page *intercept_msg_page, *register_page, *ghcb_page;
>  	void *stats_pages[2];
>  	long ret;
>  
> @@ -908,28 +908,25 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
>  	if (ret)
>  		return ret;
>  
> -	ret = hv_call_map_vp_state_page(partition->pt_id, args.vp_index,
> -					HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
> -					input_vtl_zero,
> -					&intercept_message_page);
> +	ret = hv_map_vp_state_page(partition->pt_id, args.vp_index,
> +				   HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
> +				   input_vtl_zero, &intercept_msg_page);
>  	if (ret)
>  		goto destroy_vp;
>  
>  	if (!mshv_partition_encrypted(partition)) {
> -		ret = hv_call_map_vp_state_page(partition->pt_id, args.vp_index,
> -						HV_VP_STATE_PAGE_REGISTERS,
> -						input_vtl_zero,
> -						&register_page);
> +		ret = hv_map_vp_state_page(partition->pt_id, args.vp_index,
> +					   HV_VP_STATE_PAGE_REGISTERS,
> +					   input_vtl_zero, &register_page);
>  		if (ret)
>  			goto unmap_intercept_message_page;
>  	}
>  
>  	if (mshv_partition_encrypted(partition) &&
>  	    is_ghcb_mapping_available()) {
> -		ret = hv_call_map_vp_state_page(partition->pt_id, args.vp_index,
> -						HV_VP_STATE_PAGE_GHCB,
> -						input_vtl_normal,
> -						&ghcb_page);
> +		ret = hv_map_vp_state_page(partition->pt_id, args.vp_index,
> +					   HV_VP_STATE_PAGE_GHCB,
> +					   input_vtl_normal, &ghcb_page);
>  		if (ret)
>  			goto unmap_register_page;
>  	}
> @@ -960,7 +957,7 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
>  	atomic64_set(&vp->run.vp_signaled_count, 0);
>  
>  	vp->vp_index = args.vp_index;
> -	vp->vp_intercept_msg_page = page_to_virt(intercept_message_page);
> +	vp->vp_intercept_msg_page = page_to_virt(intercept_msg_page);
>  	if (!mshv_partition_encrypted(partition))
>  		vp->vp_register_page = page_to_virt(register_page);
>  
> @@ -993,21 +990,19 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
>  	if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
>  		mshv_vp_stats_unmap(partition->pt_id, args.vp_index);
>  unmap_ghcb_page:
> -	if (mshv_partition_encrypted(partition) && is_ghcb_mapping_available()) {
> -		hv_call_unmap_vp_state_page(partition->pt_id, args.vp_index,
> -					    HV_VP_STATE_PAGE_GHCB,
> -					    input_vtl_normal);
> -	}
> +	if (mshv_partition_encrypted(partition) && is_ghcb_mapping_available())
> +		hv_unmap_vp_state_page(partition->pt_id, args.vp_index,
> +				       HV_VP_STATE_PAGE_GHCB, ghcb_page,
> +				       input_vtl_normal);
>  unmap_register_page:
> -	if (!mshv_partition_encrypted(partition)) {
> -		hv_call_unmap_vp_state_page(partition->pt_id, args.vp_index,
> -					    HV_VP_STATE_PAGE_REGISTERS,
> -					    input_vtl_zero);
> -	}
> +	if (!mshv_partition_encrypted(partition))
> +		hv_unmap_vp_state_page(partition->pt_id, args.vp_index,
> +				       HV_VP_STATE_PAGE_REGISTERS,
> +				       register_page, input_vtl_zero);
>  unmap_intercept_message_page:
> -	hv_call_unmap_vp_state_page(partition->pt_id, args.vp_index,
> -				    HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
> -				    input_vtl_zero);
> +	hv_unmap_vp_state_page(partition->pt_id, args.vp_index,
> +			       HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
> +			       intercept_msg_page, input_vtl_zero);
>  destroy_vp:
>  	hv_call_delete_vp(partition->pt_id, args.vp_index);
>  	return ret;
> @@ -1748,24 +1743,27 @@ static void destroy_partition(struct mshv_partition *partition)
>  				mshv_vp_stats_unmap(partition->pt_id, vp->vp_index);
>  
>  			if (vp->vp_register_page) {
> -				(void)hv_call_unmap_vp_state_page(partition->pt_id,
> -								  vp->vp_index,
> -								  HV_VP_STATE_PAGE_REGISTERS,
> -								  input_vtl_zero);
> +				(void)hv_unmap_vp_state_page(partition->pt_id,
> +							     vp->vp_index,
> +							     HV_VP_STATE_PAGE_REGISTERS,
> +							     virt_to_page(vp->vp_register_page),
> +							     input_vtl_zero);
>  				vp->vp_register_page = NULL;
>  			}
>  
> -			(void)hv_call_unmap_vp_state_page(partition->pt_id,
> -							  vp->vp_index,
> -							  HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
> -							  input_vtl_zero);
> +			(void)hv_unmap_vp_state_page(partition->pt_id,
> +						     vp->vp_index,
> +						     HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
> +						     virt_to_page(vp->vp_intercept_msg_page),
> +						     input_vtl_zero);
>  			vp->vp_intercept_msg_page = NULL;
>  
>  			if (vp->vp_ghcb_page) {
> -				(void)hv_call_unmap_vp_state_page(partition->pt_id,
> -								  vp->vp_index,
> -								  HV_VP_STATE_PAGE_GHCB,
> -								  input_vtl_normal);
> +				(void)hv_unmap_vp_state_page(partition->pt_id,
> +							     vp->vp_index,
> +							     HV_VP_STATE_PAGE_GHCB,
> +							     virt_to_page(vp->vp_ghcb_page),
> +							     input_vtl_normal);
>  				vp->vp_ghcb_page = NULL;
>  			}
>  
> -- 
> 2.34.1
> 

Re: [PATCH v3 4/5] mshv: Allocate vp state page for HVCALL_MAP_VP_STATE_PAGE on L1VH

[Anirudh Rayabharam]

On Tue, Sep 16, 2025 at 04:44:21PM -0700, Nuno Das Neves wrote:
> From: Jinank Jain <jinankjain@linux.microsoft.com>
> 
> Introduce mshv_use_overlay_gpfn() to check if a page needs to be
> allocated and passed to the hypervisor to map VP state pages. This is
> only needed on L1VH, and only on some (newer) versions of the
> hypervisor, hence the need to check vmm_capabilities.
> 
> Introduce functions hv_map/unmap_vp_state_page() to handle the
> allocation and freeing.
> 
> Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
> Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
> Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
> Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
> ---
>  drivers/hv/mshv_root.h         | 11 ++---
>  drivers/hv/mshv_root_hv_call.c | 61 ++++++++++++++++++++++++---
>  drivers/hv/mshv_root_main.c    | 76 +++++++++++++++++-----------------
>  3 files changed, 98 insertions(+), 50 deletions(-)

Reviewed-by: Anirudh Rayabharam <anirudh@anirudhrb.com>

[PATCH v3 5/5] mshv: Introduce new hypercall to map stats page for L1VH partitions

[Nuno Das Neves]

From: Jinank Jain <jinankjain@linux.microsoft.com>

Introduce HVCALL_MAP_STATS_PAGE2 which provides a map location (GPFN)
to map the stats to. This hypercall is required for L1VH partitions,
depending on the hypervisor version. This uses the same check as the
state page map location; mshv_use_overlay_gpfn().

Add mshv_map_vp_state_page() helpers to use this new hypercall or the
old one depending on availability.

For unmapping, the original HVCALL_UNMAP_STATS_PAGE works for both
cases.

Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
---
 drivers/hv/mshv_root.h         | 10 ++--
 drivers/hv/mshv_root_hv_call.c | 89 ++++++++++++++++++++++++++++++++--
 drivers/hv/mshv_root_main.c    | 22 +++++----
 include/hyperv/hvgdk_mini.h    |  1 +
 include/hyperv/hvhdk_mini.h    |  7 +++
 5 files changed, 109 insertions(+), 20 deletions(-)

diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
index dbe2d1d0b22f..0dfccfbe6123 100644
--- a/drivers/hv/mshv_root.h
+++ b/drivers/hv/mshv_root.h
@@ -297,11 +297,11 @@ int hv_call_connect_port(u64 port_partition_id, union hv_port_id port_id,
 int hv_call_disconnect_port(u64 connection_partition_id,
 			    union hv_connection_id connection_id);
 int hv_call_notify_port_ring_empty(u32 sint_index);
-int hv_call_map_stat_page(enum hv_stats_object_type type,
-			  const union hv_stats_object_identity *identity,
-			  void **addr);
-int hv_call_unmap_stat_page(enum hv_stats_object_type type,
-			    const union hv_stats_object_identity *identity);
+int hv_map_stats_page(enum hv_stats_object_type type,
+		      const union hv_stats_object_identity *identity,
+		      void **addr);
+int hv_unmap_stats_page(enum hv_stats_object_type type, void *page_addr,
+			const union hv_stats_object_identity *identity);
 int hv_call_modify_spa_host_access(u64 partition_id, struct page **pages,
 				   u64 page_struct_count, u32 host_access,
 				   u32 flags, u8 acquire);
diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c
index 98c6278ff151..7fb7072c071d 100644
--- a/drivers/hv/mshv_root_hv_call.c
+++ b/drivers/hv/mshv_root_hv_call.c
@@ -804,9 +804,47 @@ hv_call_notify_port_ring_empty(u32 sint_index)
 	return hv_result_to_errno(status);
 }
 
-int hv_call_map_stat_page(enum hv_stats_object_type type,
-			  const union hv_stats_object_identity *identity,
-			  void **addr)
+static int hv_call_map_stats_page2(enum hv_stats_object_type type,
+				   const union hv_stats_object_identity *identity,
+				   u64 map_location)
+{
+	unsigned long flags;
+	struct hv_input_map_stats_page2 *input;
+	u64 status;
+	int ret;
+
+	if (!map_location || !mshv_use_overlay_gpfn())
+		return -EINVAL;
+
+	do {
+		local_irq_save(flags);
+		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+		memset(input, 0, sizeof(*input));
+		input->type = type;
+		input->identity = *identity;
+		input->map_location = map_location;
+
+		status = hv_do_hypercall(HVCALL_MAP_STATS_PAGE2, input, NULL);
+
+		local_irq_restore(flags);
+		if (hv_result(status) != HV_STATUS_INSUFFICIENT_MEMORY) {
+			if (hv_result_success(status))
+				break;
+			hv_status_debug(status, "\n");
+			return hv_result_to_errno(status);
+		}
+
+		ret = hv_call_deposit_pages(NUMA_NO_NODE,
+					    hv_current_partition_id, 1);
+	} while (!ret);
+
+	return ret;
+}
+
+static int hv_call_map_stats_page(enum hv_stats_object_type type,
+				  const union hv_stats_object_identity *identity,
+				  void **addr)
 {
 	unsigned long flags;
 	struct hv_input_map_stats_page *input;
@@ -845,8 +883,36 @@ int hv_call_map_stat_page(enum hv_stats_object_type type,
 	return ret;
 }
 
-int hv_call_unmap_stat_page(enum hv_stats_object_type type,
-			    const union hv_stats_object_identity *identity)
+int hv_map_stats_page(enum hv_stats_object_type type,
+		      const union hv_stats_object_identity *identity,
+		      void **addr)
+{
+	int ret;
+	struct page *allocated_page = NULL;
+
+	if (!addr)
+		return -EINVAL;
+
+	if (mshv_use_overlay_gpfn()) {
+		allocated_page = alloc_page(GFP_KERNEL);
+		if (!allocated_page)
+			return -ENOMEM;
+
+		ret = hv_call_map_stats_page2(type, identity,
+					      page_to_pfn(allocated_page));
+		*addr = page_address(allocated_page);
+	} else {
+		ret = hv_call_map_stats_page(type, identity, addr);
+	}
+
+	if (ret && allocated_page)
+		__free_page(allocated_page);
+
+	return ret;
+}
+
+static int hv_call_unmap_stats_page(enum hv_stats_object_type type,
+				    const union hv_stats_object_identity *identity)
 {
 	unsigned long flags;
 	struct hv_input_unmap_stats_page *input;
@@ -865,6 +931,19 @@ int hv_call_unmap_stat_page(enum hv_stats_object_type type,
 	return hv_result_to_errno(status);
 }
 
+int hv_unmap_stats_page(enum hv_stats_object_type type, void *page_addr,
+			const union hv_stats_object_identity *identity)
+{
+	int ret;
+
+	ret = hv_call_unmap_stats_page(type, identity);
+
+	if (mshv_use_overlay_gpfn() && page_addr)
+		__free_page(virt_to_page(page_addr));
+
+	return ret;
+}
+
 int hv_call_modify_spa_host_access(u64 partition_id, struct page **pages,
 				   u64 page_struct_count, u32 host_access,
 				   u32 flags, u8 acquire)
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index 52f69eace9b9..cf46f6772a89 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -841,7 +841,8 @@ mshv_vp_release(struct inode *inode, struct file *filp)
 	return 0;
 }
 
-static void mshv_vp_stats_unmap(u64 partition_id, u32 vp_index)
+static void mshv_vp_stats_unmap(u64 partition_id, u32 vp_index,
+				void *stats_pages[])
 {
 	union hv_stats_object_identity identity = {
 		.vp.partition_id = partition_id,
@@ -849,10 +850,10 @@ static void mshv_vp_stats_unmap(u64 partition_id, u32 vp_index)
 	};
 
 	identity.vp.stats_area_type = HV_STATS_AREA_SELF;
-	hv_call_unmap_stat_page(HV_STATS_OBJECT_VP, &identity);
+	hv_unmap_stats_page(HV_STATS_OBJECT_VP, NULL, &identity);
 
 	identity.vp.stats_area_type = HV_STATS_AREA_PARENT;
-	hv_call_unmap_stat_page(HV_STATS_OBJECT_VP, &identity);
+	hv_unmap_stats_page(HV_STATS_OBJECT_VP, NULL, &identity);
 }
 
 static int mshv_vp_stats_map(u64 partition_id, u32 vp_index,
@@ -865,14 +866,14 @@ static int mshv_vp_stats_map(u64 partition_id, u32 vp_index,
 	int err;
 
 	identity.vp.stats_area_type = HV_STATS_AREA_SELF;
-	err = hv_call_map_stat_page(HV_STATS_OBJECT_VP, &identity,
-				    &stats_pages[HV_STATS_AREA_SELF]);
+	err = hv_map_stats_page(HV_STATS_OBJECT_VP, &identity,
+				&stats_pages[HV_STATS_AREA_SELF]);
 	if (err)
 		return err;
 
 	identity.vp.stats_area_type = HV_STATS_AREA_PARENT;
-	err = hv_call_map_stat_page(HV_STATS_OBJECT_VP, &identity,
-				    &stats_pages[HV_STATS_AREA_PARENT]);
+	err = hv_map_stats_page(HV_STATS_OBJECT_VP, &identity,
+				&stats_pages[HV_STATS_AREA_PARENT]);
 	if (err)
 		goto unmap_self;
 
@@ -880,7 +881,7 @@ static int mshv_vp_stats_map(u64 partition_id, u32 vp_index,
 
 unmap_self:
 	identity.vp.stats_area_type = HV_STATS_AREA_SELF;
-	hv_call_unmap_stat_page(HV_STATS_OBJECT_VP, &identity);
+	hv_unmap_stats_page(HV_STATS_OBJECT_VP, NULL, &identity);
 	return err;
 }
 
@@ -988,7 +989,7 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
 	kfree(vp);
 unmap_stats_pages:
 	if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
-		mshv_vp_stats_unmap(partition->pt_id, args.vp_index);
+		mshv_vp_stats_unmap(partition->pt_id, args.vp_index, stats_pages);
 unmap_ghcb_page:
 	if (mshv_partition_encrypted(partition) && is_ghcb_mapping_available())
 		hv_unmap_vp_state_page(partition->pt_id, args.vp_index,
@@ -1740,7 +1741,8 @@ static void destroy_partition(struct mshv_partition *partition)
 				continue;
 
 			if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
-				mshv_vp_stats_unmap(partition->pt_id, vp->vp_index);
+				mshv_vp_stats_unmap(partition->pt_id, vp->vp_index,
+						    (void **)vp->vp_stats_pages);
 
 			if (vp->vp_register_page) {
 				(void)hv_unmap_vp_state_page(partition->pt_id,
diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
index ff4325fb623a..f66565106d21 100644
--- a/include/hyperv/hvgdk_mini.h
+++ b/include/hyperv/hvgdk_mini.h
@@ -493,6 +493,7 @@ union hv_vp_assist_msr_contents {	 /* HV_REGISTER_VP_ASSIST_PAGE */
 #define HVCALL_GET_PARTITION_PROPERTY_EX		0x0101
 #define HVCALL_MMIO_READ				0x0106
 #define HVCALL_MMIO_WRITE				0x0107
+#define HVCALL_MAP_STATS_PAGE2				0x0131
 
 /* HV_HYPERCALL_INPUT */
 #define HV_HYPERCALL_RESULT_MASK	GENMASK_ULL(15, 0)
diff --git a/include/hyperv/hvhdk_mini.h b/include/hyperv/hvhdk_mini.h
index bf2ce27dfcc5..064bf735cab6 100644
--- a/include/hyperv/hvhdk_mini.h
+++ b/include/hyperv/hvhdk_mini.h
@@ -177,6 +177,13 @@ struct hv_input_map_stats_page {
 	union hv_stats_object_identity identity;
 } __packed;
 
+struct hv_input_map_stats_page2 {
+	u32 type; /* enum hv_stats_object_type */
+	u32 padding;
+	union hv_stats_object_identity identity;
+	u64 map_location;
+} __packed;
+
 struct hv_output_map_stats_page {
 	u64 map_location;
 } __packed;
-- 
2.34.1

Re: [PATCH v3 5/5] mshv: Introduce new hypercall to map stats page for L1VH partitions

[Stanislav Kinsburskii]

On Tue, Sep 16, 2025 at 04:44:22PM -0700, Nuno Das Neves wrote:
> From: Jinank Jain <jinankjain@linux.microsoft.com>
> 

<snip>

> +static int hv_call_map_stats_page2(enum hv_stats_object_type type,
> +				   const union hv_stats_object_identity *identity,
> +				   u64 map_location)
> +{
> +	unsigned long flags;
> +	struct hv_input_map_stats_page2 *input;
> +	u64 status;
> +	int ret;
> +
> +	if (!map_location || !mshv_use_overlay_gpfn())
> +		return -EINVAL;
> +
> +	do {
> +		local_irq_save(flags);
> +		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
> +
> +		memset(input, 0, sizeof(*input));
> +		input->type = type;
> +		input->identity = *identity;
> +		input->map_location = map_location;
> +
> +		status = hv_do_hypercall(HVCALL_MAP_STATS_PAGE2, input, NULL);
> +
> +		local_irq_restore(flags);
> +		if (hv_result(status) != HV_STATUS_INSUFFICIENT_MEMORY) {
> +			if (hv_result_success(status))
> +				break;
> +			hv_status_debug(status, "\n");

It looks more natural to check for success first and break the loop, and
only then handle errors.
Maybe even set ret for both success and error messages and break and
handle only the unsufficient memory status.

> @@ -865,6 +931,19 @@ int hv_call_unmap_stat_page(enum hv_stats_object_type type,
>  	return hv_result_to_errno(status);
>  }
>  
> +int hv_unmap_stats_page(enum hv_stats_object_type type, void *page_addr,
> +			const union hv_stats_object_identity *identity)
> +{

Should this function be type of void?

Thanks,
Stanislav

Re: [PATCH v3 5/5] mshv: Introduce new hypercall to map stats page for L1VH partitions

[Nuno Das Neves]

On 9/18/2025 12:53 PM, Stanislav Kinsburskii wrote:
> On Tue, Sep 16, 2025 at 04:44:22PM -0700, Nuno Das Neves wrote:
>> From: Jinank Jain <jinankjain@linux.microsoft.com>
>>
> 
> <snip>
> 
>> +static int hv_call_map_stats_page2(enum hv_stats_object_type type,
>> +				   const union hv_stats_object_identity *identity,
>> +				   u64 map_location)
>> +{
>> +	unsigned long flags;
>> +	struct hv_input_map_stats_page2 *input;
>> +	u64 status;
>> +	int ret;
>> +
>> +	if (!map_location || !mshv_use_overlay_gpfn())
>> +		return -EINVAL;
>> +
>> +	do {
>> +		local_irq_save(flags);
>> +		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
>> +
>> +		memset(input, 0, sizeof(*input));
>> +		input->type = type;
>> +		input->identity = *identity;
>> +		input->map_location = map_location;
>> +
>> +		status = hv_do_hypercall(HVCALL_MAP_STATS_PAGE2, input, NULL);
>> +
>> +		local_irq_restore(flags);
>> +		if (hv_result(status) != HV_STATUS_INSUFFICIENT_MEMORY) {
>> +			if (hv_result_success(status))
>> +				break;
>> +			hv_status_debug(status, "\n");
> 
> It looks more natural to check for success first and break the loop, and
> only then handle errors.
> Maybe even set ret for both success and error messages and break and
> handle only the unsufficient memory status.
> 

Something like this?

	local_irq_restore(flags);

	ret = hv_result_to_errno(status);

	if (!ret)
		break;

	if (hv_result(status) != HV_STATUS_INSUFFICIENT_MEMORY) {
		hv_status_debug(status, "\n");
		break;
	}

	ret = hv_call_deposit_pages(NUMA_NO_NODE,
				    hv_current_partition_id, 1);

>> @@ -865,6 +931,19 @@ int hv_call_unmap_stat_page(enum hv_stats_object_type type,
>>  	return hv_result_to_errno(status);
>>  }
>>  
>> +int hv_unmap_stats_page(enum hv_stats_object_type type, void *page_addr,
>> +			const union hv_stats_object_identity *identity)
>> +{
> 
> Should this function be type of void?
> 

The return type is consistent with the other hypercall helpers. It's true that
in practice we don't ever check if the unmap succeeded. I think it's fine as-is.

> Thanks,
> Stanislav