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mshv: Ignore second stats page map result failure

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Older versions of the hypervisor do not have a concept of separate SELF
and PARENT stats areas. In this case, mapping the HV_STATS_AREA_SELF page
is sufficient - it's the only page and it contains all available stats.

Mapping HV_STATS_AREA_PARENT returns HV_STATUS_INVALID_PARAMETER which
currently causes module init to fail on older hypevisor versions.

Detect this case and gracefully fall back to populating
stats_pages[HV_STATS_AREA_PARENT] with the already-mapped SELF page.

Add comments to clarify the behavior, including a clarification of why
this isn't needed for hv_call_map_stats_page2() which always supports
PARENT and SELF areas.

Signed-off-by: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Acked-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Purna Pavan Chandra Aekkaladevi 2026-01-28 10:11:40 -08:00 committed by Wei Liu
parent 8d1294d4b5
commit 7538b80e5a
2 changed files with 51 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
drivers/hv/mshv_root_hv_call.c
View File

@ -813,6 +813,13 @@ hv_call_notify_port_ring_empty(u32 sint_index)
return hv_result_to_errno(status);
}
/*
* Equivalent of hv_call_map_stats_page() for cases when the caller provides
* the map location.
*
* NOTE: This is a newer hypercall that always supports SELF and PARENT stats
* areas, unlike hv_call_map_stats_page().
*/
static int hv_call_map_stats_page2(enum hv_stats_object_type type,
const union hv_stats_object_identity *identity,
u64 map_location)
@ -855,6 +862,34 @@ static int hv_call_map_stats_page2(enum hv_stats_object_type type,
return ret;
}
static int
hv_stats_get_area_type(enum hv_stats_object_type type,
const union hv_stats_object_identity *identity)
{
switch (type) {
case HV_STATS_OBJECT_HYPERVISOR:
return identity->hv.stats_area_type;
case HV_STATS_OBJECT_LOGICAL_PROCESSOR:
return identity->lp.stats_area_type;
case HV_STATS_OBJECT_PARTITION:
return identity->partition.stats_area_type;
case HV_STATS_OBJECT_VP:
return identity->vp.stats_area_type;
}
return -EINVAL;
}
/*
* Map a stats page, where the page location is provided by the hypervisor.
*
* NOTE: The concept of separate SELF and PARENT stats areas does not exist on
* older hypervisor versions. All the available stats information can be found
* on the SELF page. When attempting to map the PARENT area on a hypervisor
* that doesn't support it, return "success" but with a NULL address. The
* caller should check for this case and instead fallback to the SELF area
* alone.
*/
static int hv_call_map_stats_page(enum hv_stats_object_type type,
const union hv_stats_object_identity *identity,
void **addr)
@ -863,7 +898,7 @@ static int hv_call_map_stats_page(enum hv_stats_object_type type,
struct hv_input_map_stats_page *input;
struct hv_output_map_stats_page *output;
u64 status, pfn;
int ret = 0;
int hv_status, ret = 0;
do {
local_irq_save(flags);
@ -878,11 +913,20 @@ static int hv_call_map_stats_page(enum hv_stats_object_type type,
pfn = output->map_location;
local_irq_restore(flags);
if (hv_result(status) != HV_STATUS_INSUFFICIENT_MEMORY) {
ret = hv_result_to_errno(status);
hv_status = hv_result(status);
if (hv_status != HV_STATUS_INSUFFICIENT_MEMORY) {
if (hv_result_success(status))
break;
return ret;
if (hv_stats_get_area_type(type, identity) == HV_STATS_AREA_PARENT &&
hv_status == HV_STATUS_INVALID_PARAMETER) {
*addr = NULL;
return 0;
}
hv_status_debug(status, "\n");
return hv_result_to_errno(status);
}
ret = hv_call_deposit_pages(NUMA_NO_NODE,

3
drivers/hv/mshv_root_main.c
View File

@ -993,6 +993,9 @@ static int mshv_vp_stats_map(u64 partition_id, u32 vp_index,
if (err)
goto unmap_self;
if (!stats_pages[HV_STATS_AREA_PARENT])
stats_pages[HV_STATS_AREA_PARENT] = stats_pages[HV_STATS_AREA_SELF];
return 0;
unmap_self: