From 7538b80e5a4b473b73428d13b3a47ceaad9a8a7c Mon Sep 17 00:00:00 2001 From: Purna Pavan Chandra Aekkaladevi Date: Wed, 28 Jan 2026 10:11:40 -0800 Subject: [PATCH] mshv: Ignore second stats page map result failure 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 Signed-off-by: Nuno Das Neves Reviewed-by: Stanislav Kinsburskii Acked-by: Stanislav Kinsburskii Reviewed-by: Michael Kelley Signed-off-by: Wei Liu --- drivers/hv/mshv_root_hv_call.c | 52 +++++++++++++++++++++++++++++++--- drivers/hv/mshv_root_main.c | 3 ++ 2 files changed, 51 insertions(+), 4 deletions(-) diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c index 598eaff4ff299..1f93b94d7580c 100644 --- a/drivers/hv/mshv_root_hv_call.c +++ b/drivers/hv/mshv_root_hv_call.c @@ -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, diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c index 681b58154d5ea..d3e8a66443ad6 100644 --- a/drivers/hv/mshv_root_main.c +++ b/drivers/hv/mshv_root_main.c @@ -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: -- 2.47.3