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Message-ID: <8d141a6a-d06f-f91a-686b-82f8f0facabc@linux.microsoft.com>
Date: Tue, 27 Jan 2026 11:44:25 -0800
From: Mukesh R <mrathor@...ux.microsoft.com>
To: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
Cc: kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
decui@...rosoft.com, longli@...rosoft.com, linux-hyperv@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] mshv: Introduce hv_deposit_memory helper functions
On 1/27/26 10:30, Stanislav Kinsburskii wrote:
> On Mon, Jan 26, 2026 at 06:06:23PM -0800, Mukesh R wrote:
>> On 1/25/26 14:41, Stanislav Kinsburskii wrote:
>>> On Fri, Jan 23, 2026 at 04:33:39PM -0800, Mukesh R wrote:
>>>> On 1/22/26 17:35, Stanislav Kinsburskii wrote:
>>>>> Introduce hv_deposit_memory_node() and hv_deposit_memory() helper
>>>>> functions to handle memory deposition with proper error handling.
>>>>>
>>>>> The new hv_deposit_memory_node() function takes the hypervisor status
>>>>> as a parameter and validates it before depositing pages. It checks for
>>>>> HV_STATUS_INSUFFICIENT_MEMORY specifically and returns an error for
>>>>> unexpected status codes.
>>>>>
>>>>> This is a precursor patch to new out-of-memory error codes support.
>>>>> No functional changes intended.
>>>>>
>>>>> Signed-off-by: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
>>>>> ---
>>>>> drivers/hv/hv_proc.c | 22 ++++++++++++++++++++--
>>>>> drivers/hv/mshv_root_hv_call.c | 25 +++++++++----------------
>>>>> drivers/hv/mshv_root_main.c | 3 +--
>>>>> include/asm-generic/mshyperv.h | 10 ++++++++++
>>>>> 4 files changed, 40 insertions(+), 20 deletions(-)
>>>>>
>>>>> diff --git a/drivers/hv/hv_proc.c b/drivers/hv/hv_proc.c
>>>>> index 80c66d1c74d5..c0c2bfc80d77 100644
>>>>> --- a/drivers/hv/hv_proc.c
>>>>> +++ b/drivers/hv/hv_proc.c
>>>>> @@ -110,6 +110,23 @@ int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
>>>>> }
>>>>> EXPORT_SYMBOL_GPL(hv_call_deposit_pages);
>>>>> +int hv_deposit_memory_node(int node, u64 partition_id,
>>>>> + u64 hv_status)
>>>>> +{
>>>>> + u32 num_pages;
>>>>> +
>>>>> + switch (hv_result(hv_status)) {
>>>>> + case HV_STATUS_INSUFFICIENT_MEMORY:
>>>>> + num_pages = 1;
>>>>> + break;
>>>>> + default:
>>>>> + hv_status_err(hv_status, "Unexpected!\n");
>>>>> + return -ENOMEM;
>>>>> + }
>>>>> + return hv_call_deposit_pages(node, partition_id, num_pages);
>>>>> +}
>>>>> +EXPORT_SYMBOL_GPL(hv_deposit_memory_node);
>>>>> +
>>>>
>>>> Different hypercalls may want to deposit different number of pages in one
>>>> shot. As feature evolves, page sizes get mixed, we'd almost need that
>>>> flexibility. So, imo, either we just don't do this for now, or add num pages
>>>> parameter to be passed down.
>>>>
>>>
>>> What you do mean by "page sizes get mixed"?
>>> A helper to deposit num pages already exists: its
>>> hv_call_deposit_pages().
>>
>> My point, you are removing number of pages, and we may want to keep
>> that so one can quickly play around and change them.
>>
>> - ret = hv_call_deposit_pages(NUMA_NO_NODE,
>> - pt_id, 1);
>> + ret = hv_deposit_memory(pt_id, status);
>>
>> For example, in hv_call_initialize_partition() we may realize after
>> some analysis that depositing 2 pages or 4 pages is much better.
>>
>
> We have been using this 1-page deposit logic from the beginning. To
> change the number of pages, simply replace hv_deposit_memory with
> hv_call_deposit_pages and specify the desired number of pages.
You could perhaps rename it to hv_deposit_page().
> The proposed approach reduces code duplication and is less error-prone,
> as there are multiple error codes to handle. Consolidating the logic
> also makes the driver more robust.
>
>
> Thanks, Stanislav
>
>>> Thanks,
>>> Stanislav
>>>
>>>> Thanks,
>>>> -Mukesh
>>>>
>>>>
>>>>
>>>>> bool hv_result_oom(u64 status)
>>>>> {
>>>>> switch (hv_result(status)) {
>>>>> @@ -155,7 +172,8 @@ int hv_call_add_logical_proc(int node, u32 lp_index, u32 apic_id)
>>>>> }
>>>>> break;
>>>>> }
>>>>> - ret = hv_call_deposit_pages(node, hv_current_partition_id, 1);
>>>>> + ret = hv_deposit_memory_node(node, hv_current_partition_id,
>>>>> + status);
>>>>> } while (!ret);
>>>>> return ret;
>>>>> @@ -197,7 +215,7 @@ int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags)
>>>>> }
>>>>> break;
>>>>> }
>>>>> - ret = hv_call_deposit_pages(node, partition_id, 1);
>>>>> + ret = hv_deposit_memory_node(node, partition_id, status);
>>>>> } while (!ret);
>>>>> diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c
>>>>> index 58c5cbf2e567..06f2bac8039d 100644
>>>>> --- a/drivers/hv/mshv_root_hv_call.c
>>>>> +++ b/drivers/hv/mshv_root_hv_call.c
>>>>> @@ -123,8 +123,7 @@ int hv_call_create_partition(u64 flags,
>>>>> break;
>>>>> }
>>>>> local_irq_restore(irq_flags);
>>>>> - ret = hv_call_deposit_pages(NUMA_NO_NODE,
>>>>> - hv_current_partition_id, 1);
>>>>> + ret = hv_deposit_memory(hv_current_partition_id, status);
>>>>> } while (!ret);
>>>>> return ret;
>>>>> @@ -151,7 +150,7 @@ int hv_call_initialize_partition(u64 partition_id)
>>>>> ret = hv_result_to_errno(status);
>>>>> break;
>>>>> }
>>>>> - ret = hv_call_deposit_pages(NUMA_NO_NODE, partition_id, 1);
>>>>> + ret = hv_deposit_memory(partition_id, status);
>>>>> } while (!ret);
>>>>> return ret;
>>>>> @@ -465,8 +464,7 @@ int hv_call_get_vp_state(u32 vp_index, u64 partition_id,
>>>>> }
>>>>> local_irq_restore(flags);
>>>>> - ret = hv_call_deposit_pages(NUMA_NO_NODE,
>>>>> - partition_id, 1);
>>>>> + ret = hv_deposit_memory(partition_id, status);
>>>>> } while (!ret);
>>>>> return ret;
>>>>> @@ -525,8 +523,7 @@ int hv_call_set_vp_state(u32 vp_index, u64 partition_id,
>>>>> }
>>>>> local_irq_restore(flags);
>>>>> - ret = hv_call_deposit_pages(NUMA_NO_NODE,
>>>>> - partition_id, 1);
>>>>> + ret = hv_deposit_memory(partition_id, status);
>>>>> } while (!ret);
>>>>> return ret;
>>>>> @@ -573,7 +570,7 @@ static int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
>>>>> local_irq_restore(flags);
>>>>> - ret = hv_call_deposit_pages(NUMA_NO_NODE, partition_id, 1);
>>>>> + ret = hv_deposit_memory(partition_id, status);
>>>>> } while (!ret);
>>>>> return ret;
>>>>> @@ -722,8 +719,7 @@ hv_call_create_port(u64 port_partition_id, union hv_port_id port_id,
>>>>> ret = hv_result_to_errno(status);
>>>>> break;
>>>>> }
>>>>> - ret = hv_call_deposit_pages(NUMA_NO_NODE, port_partition_id, 1);
>>>>> -
>>>>> + ret = hv_deposit_memory(port_partition_id, status);
>>>>> } while (!ret);
>>>>> return ret;
>>>>> @@ -776,8 +772,7 @@ hv_call_connect_port(u64 port_partition_id, union hv_port_id port_id,
>>>>> ret = hv_result_to_errno(status);
>>>>> break;
>>>>> }
>>>>> - ret = hv_call_deposit_pages(NUMA_NO_NODE,
>>>>> - connection_partition_id, 1);
>>>>> + ret = hv_deposit_memory(connection_partition_id, status);
>>>>> } while (!ret);
>>>>> return ret;
>>>>> @@ -848,8 +843,7 @@ static int hv_call_map_stats_page2(enum hv_stats_object_type type,
>>>>> break;
>>>>> }
>>>>> - ret = hv_call_deposit_pages(NUMA_NO_NODE,
>>>>> - hv_current_partition_id, 1);
>>>>> + ret = hv_deposit_memory(hv_current_partition_id, status);
>>>>> } while (!ret);
>>>>> return ret;
>>>>> @@ -885,8 +879,7 @@ static int hv_call_map_stats_page(enum hv_stats_object_type type,
>>>>> return ret;
>>>>> }
>>>>> - ret = hv_call_deposit_pages(NUMA_NO_NODE,
>>>>> - hv_current_partition_id, 1);
>>>>> + ret = hv_deposit_memory(hv_current_partition_id, status);
>>>>> if (ret)
>>>>> return ret;
>>>>> } while (!ret);
>>>>> diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
>>>>> index f4697497f83e..5fc572e31cd7 100644
>>>>> --- a/drivers/hv/mshv_root_main.c
>>>>> +++ b/drivers/hv/mshv_root_main.c
>>>>> @@ -264,8 +264,7 @@ static int mshv_ioctl_passthru_hvcall(struct mshv_partition *partition,
>>>>> if (!hv_result_oom(status))
>>>>> ret = hv_result_to_errno(status);
>>>>> else
>>>>> - ret = hv_call_deposit_pages(NUMA_NO_NODE,
>>>>> - pt_id, 1);
>>>>> + ret = hv_deposit_memory(pt_id, status);
>>>>> } while (!ret);
>>>>> args.status = hv_result(status);
>>>>> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
>>>>> index b73352a7fc9e..c8e8976839f8 100644
>>>>> --- a/include/asm-generic/mshyperv.h
>>>>> +++ b/include/asm-generic/mshyperv.h
>>>>> @@ -344,6 +344,7 @@ static inline bool hv_parent_partition(void)
>>>>> }
>>>>> bool hv_result_oom(u64 status);
>>>>> +int hv_deposit_memory_node(int node, u64 partition_id, u64 status);
>>>>> int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages);
>>>>> int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id);
>>>>> int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags);
>>>>> @@ -353,6 +354,10 @@ 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_oom(u64 status) { return false; }
>>>>> +static inline int hv_deposit_memory_node(int node, u64 partition_id, u64 status)
>>>>> +{
>>>>> + return -EOPNOTSUPP;
>>>>> +}
>>>>> static inline int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
>>>>> {
>>>>> return -EOPNOTSUPP;
>>>>> @@ -367,6 +372,11 @@ static inline int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u3
>>>>> }
>>>>> #endif /* CONFIG_MSHV_ROOT */
>>>>> +static inline int hv_deposit_memory(u64 partition_id, u64 status)
>>>>> +{
>>>>> + return hv_deposit_memory_node(NUMA_NO_NODE, partition_id, status);
>>>>> +}
>>>>> +
>>>>> #if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
>>>>> u8 __init get_vtl(void);
>>>>> #else
>>>>>
>>>>>
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