Re: [PATCH V4 1/5] mshv: Add gfp flags to deposit memory logic

[Jacob Pan <jacob.pan@linux.microsoft.com>]

Hi Mukesh,

On Wed,  4 Nov 2026 18:01:02 -0800
Mukesh R <mrathor@linux.microsoft.com> wrote:

> Currently GFP_KERNEL is hard coded in hv_alloc_dep_pages(). Add
> gfp_flags parameter so it can be called in atomic context from
> map_pages callback in struct iommu_domain_ops and other places in
> future. A new function hv_deposit_memory_gfp() is added to facilitate
> this, so hv_deposit_memory() can continue to function as is.
> 
> Signed-off-by: Mukesh R <mrathor@linux.microsoft.com>
> ---
>  drivers/hv/hv_proc.c           | 20 +++++++++++---------
>  include/asm-generic/mshyperv.h | 14 +++++++++++---
>  2 files changed, 22 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/hv/hv_proc.c b/drivers/hv/hv_proc.c
> index f811bb5c42a1..8380e9050f46 100644
> --- a/drivers/hv/hv_proc.c
> +++ b/drivers/hv/hv_proc.c
> @@ -22,7 +22,7 @@
>   * Returns: number of pages allocated or -ENOMEM
>   */
>  static int hv_alloc_dep_pages(int node, u64 *pfna, u64 *lastpfnp,
> int num_pages,
> -			      bool single)
> +			      bool single, gfp_t gfp_flags)
>  {
>  	struct page *page;
>  	int num_allocd, count = 0;
> @@ -37,7 +37,6 @@ static int hv_alloc_dep_pages(int node, u64 *pfna,
> u64 *lastpfnp, int num_pages, while (num_pages) {
>  		/* Find highest order we can actually allocate */
>  		int order = 31 - __builtin_clz(num_pages);
> -		gfp_t gfp_flags = GFP_KERNEL;
>  
>  		if (!single)
>  			gfp_flags |= __GFP_NOWARN;
> @@ -81,7 +80,8 @@ static int hv_alloc_dep_pages(int node, u64 *pfna,
> u64 *lastpfnp, int num_pages,
>   * so we must split that also. Lastly,
> HV_MAX_CONTIGUOUS_ALLOCATION_PAGES is
>   * not guaranteed to always be power of 2.
>   */
> -static int hv_call_deposit_pages(int node, u64 partition_id, bool
> contiguous) +static int hv_call_deposit_pages(int node, u64
> partition_id, bool contiguous,
> +				 gfp_t gfp_flags)
>  {
>  	struct hv_deposit_memory *hc_input;
>  	int i, rc, num_pages;
> @@ -98,14 +98,15 @@ static int hv_call_deposit_pages(int node, u64
> partition_id, bool contiguous) num_pages = HV_DEPOSIT_MAX;
>  	}
>  
> -	hc_input = (struct hv_deposit_memory
> *)get_zeroed_page(GFP_KERNEL);
> +	hc_input = (struct hv_deposit_memory
> *)get_zeroed_page(gfp_flags); if (hc_input == NULL)
>  		return -ENOMEM;
>  
>  	hc_input->partition_id = partition_id;
>  	pfna = hc_input->gpa_page_list;
>  
> -	rc = hv_alloc_dep_pages(node, pfna, &lastpfn, num_pages,
> contiguous);
> +	rc = hv_alloc_dep_pages(node, pfna, &lastpfn, num_pages,
> contiguous,
> +				gfp_flags);
>  	if (rc < 0)
>  		goto out_free;
>  
> @@ -159,7 +160,7 @@ static int hv_call_deposit_pages(int node, u64
> partition_id, bool contiguous) return rc;
>  }
>  
> -int hv_deposit_memory_node(int node, u64 pt_id, u64 hv_status)
> +int hv_deposit_memory_node(int node, u64 pt_id, u64 hv_status, gfp_t
> gfp_flags) {
>  	int result = hv_result(hv_status);
>  	bool contiguous = false;
> @@ -179,7 +180,7 @@ int hv_deposit_memory_node(int node, u64 pt_id,
> u64 hv_status) result ==
> HV_STATUS_INSUFFICIENT_CONTIGUOUS_ROOT_MEMORY) contiguous = true;
>  
> -	return hv_call_deposit_pages(node, pt_id, contiguous);
> +	return hv_call_deposit_pages(node, pt_id, contiguous,
> gfp_flags); }
>  EXPORT_SYMBOL_GPL(hv_deposit_memory_node);
>  
> @@ -232,7 +233,7 @@ int hv_call_add_logical_proc(int node, u32
> lp_index, u32 apic_id) break;
>  		}
>  		ret = hv_deposit_memory_node(node,
> hv_current_partition_id,
> -					     status);
> +					     status, GFP_KERNEL);
>  	} while (!ret);
>  
>  	return ret;
> @@ -266,7 +267,8 @@ int hv_call_create_vp(int node, u64 partition_id,
> u32 vp_index, u32 flags) }
>  			break;
>  		}
> -		ret = hv_deposit_memory_node(node, partition_id,
> status);
> +		ret = hv_deposit_memory_node(node, partition_id,
> status,
> +					     GFP_KERNEL);
>  
>  	} while (!ret);
>  
> diff --git a/include/asm-generic/mshyperv.h
> b/include/asm-generic/mshyperv.h index 4c9f3353074a..2584e693d7b3
> 100644 --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -346,7 +346,7 @@ static inline bool hv_parent_partition(void)
>  }
>  
>  bool hv_result_needs_memory(u64 status);
> -int hv_deposit_memory_node(int node, u64 partition_id, u64 status);
> +int hv_deposit_memory_node(int node, u64 partition_id, u64 status,
> gfp_t gfp); int hv_call_add_logical_proc(int node, u32 lp_index, u32
> acpi_id); int hv_call_notify_all_processors_started(void);
>  bool hv_lp_exists(u32 lp_index);
> @@ -357,7 +357,8 @@ static inline bool hv_root_partition(void) {
> return false; } static inline bool hv_l1vh_partition(void) { return
> false; } static inline bool hv_parent_partition(void) { return false;
> } static inline bool hv_result_needs_memory(u64 status) { return
> false; } -static inline int hv_deposit_memory_node(int node, u64
> partition_id, u64 status) +static inline int
> hv_deposit_memory_node(int node, u64 partition_id, u64 status,
> +					 gfp_t gfp)
>  {
>  	return -EOPNOTSUPP;
>  }
> @@ -379,9 +380,16 @@ static inline int hv_call_create_vp(int node,
> u64 partition_id, u32 vp_index, u3 }
>  #endif /* CONFIG_MSHV_ROOT */
>  
> +/* Generic deposit function with no default numa node and GFP_KERNEL
> */ static inline int hv_deposit_memory(u64 partition_id, u64 status)
>  {
> -	return hv_deposit_memory_node(NUMA_NO_NODE, partition_id,
> status);
> +	return hv_deposit_memory_node(NUMA_NO_NODE, partition_id,
> status,
> +				      GFP_KERNEL);
> +}
> +
> +static inline int hv_deposit_memory_gfp(u64 partition_id, u64
> status, gfp_t gfp) +{
> +	return hv_deposit_memory_node(NUMA_NO_NODE, partition_id,
> status, gfp); }
>  
>  #if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
nit: no user for hv_deposit_memory_gfp here.
IMHO, hv_deposit_memory_gfp() should be introduced in patch 5/5, where
hv_iommu_map_pages()  first calls it:
ret = hv_deposit_memory_gfp(hv_current_partition_id, status, gfp);

Other than that,

Reviewed-by: Jacob Pan <jacob.pan@linux.microsoft.com>