Re: [PATCH 3/6] mshv: Add the HVCALL_GET_PARTITION_PROPERTY_EX hypercall

[Anirudh Rayabharam <anirudh@anirudhrb.com>]

On Thu, Aug 28, 2025 at 05:43:47PM -0700, Nuno Das Neves wrote:
> 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>
> ---
>  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 1c38576a673c..7589b1ff3515 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 79b7324e4ef5..1bde0aa102ec 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 57f3f9c2a685..fd3555def008 100644
> --- a/include/hyperv/hvhdk.h
> +++ b/include/hyperv/hvhdk.h
> @@ -411,6 +411,46 @@ 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
> 

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