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Message-ID: <12bb86c5-51ea-6f5c-cb64-162383ae5454@linux.microsoft.com>
Date: Thu, 29 Jan 2026 18:49:25 -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 1/28/26 15:18, Stanislav Kinsburskii wrote:
> On Tue, Jan 27, 2026 at 11:44:25AM -0800, Mukesh R wrote:
>> 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().
>>
>
> Yes, this would be a good name, but unfortunately we can now receive
> statuses like HV_STATUS_INSUFFICIENT_CONTIGUOUS_MEMORY, where we need to
> deposit at least 8 consecutive pages. There is also another pair of
> status codes for required root pages, even when a guest partition-related
> hypercall is performed (see the next patch for details).
> This new helper is intended to cover all such cases, instead of branching
> for all these different cases in every function.
Got it, thanks.
> Thanks,
> Stanislav
>
>
>>> 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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