diff options
| author | Naman Jain <namjain@linux.microsoft.com> | 2026-04-06 09:24:59 +0000 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2026-04-14 04:44:31 +0000 |
| commit | 404cd6bffe17e25e0f94ed2775ffdd6cd10ac3fd (patch) | |
| tree | 11f5a31ff97c3da499e22f3afd07924846eac0fb /drivers/hv | |
| parent | ca5ee0e918115fb5cf626d75461d9fca06e06caf (diff) | |
mshv_vtl: Fix vmemmap_shift exceeding MAX_FOLIO_ORDER
When registering VTL0 memory via MSHV_ADD_VTL0_MEMORY, the kernel
computes pgmap->vmemmap_shift as the number of trailing zeros in the
OR of start_pfn and last_pfn, intending to use the largest compound
page order both endpoints are aligned to.
However, this value is not clamped to MAX_FOLIO_ORDER, so a
sufficiently aligned range (e.g. physical range
[0x800000000000, 0x800080000000), corresponding to start_pfn=0x800000000
with 35 trailing zeros) can produce a shift larger than what
memremap_pages() accepts, triggering a WARN and returning -EINVAL:
WARNING: ... memremap_pages+0x512/0x650
requested folio size unsupported
The MAX_FOLIO_ORDER check was added by
commit 646b67d57589 ("mm/memremap: reject unreasonable folio/compound
page sizes in memremap_pages()").
Fix this by clamping vmemmap_shift to MAX_FOLIO_ORDER so we always
request the largest order the kernel supports, in those cases, rather
than an out-of-range value.
Also fix the error path to propagate the actual error code from
devm_memremap_pages() instead of hard-coding -EFAULT, which was
masking the real -EINVAL return.
Fixes: 7bfe3b8ea6e3 ("Drivers: hv: Introduce mshv_vtl driver")
Cc: stable@vger.kernel.org
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'drivers/hv')
| -rw-r--r-- | drivers/hv/mshv_vtl_main.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c index 5856975f32e1..c19400701467 100644 --- a/drivers/hv/mshv_vtl_main.c +++ b/drivers/hv/mshv_vtl_main.c @@ -386,7 +386,6 @@ static int mshv_vtl_ioctl_add_vtl0_mem(struct mshv_vtl *vtl, void __user *arg) if (copy_from_user(&vtl0_mem, arg, sizeof(vtl0_mem))) return -EFAULT; - /* vtl0_mem.last_pfn is excluded in the pagemap range for VTL0 as per design */ if (vtl0_mem.last_pfn <= vtl0_mem.start_pfn) { dev_err(vtl->module_dev, "range start pfn (%llx) > end pfn (%llx)\n", vtl0_mem.start_pfn, vtl0_mem.last_pfn); @@ -397,6 +396,10 @@ static int mshv_vtl_ioctl_add_vtl0_mem(struct mshv_vtl *vtl, void __user *arg) if (!pgmap) return -ENOMEM; + /* + * vtl0_mem.last_pfn is excluded in the pagemap range for VTL0 as per design. + * last_pfn is not reserved or wasted, and reflects 'start_pfn + size' of pagemap range. + */ pgmap->ranges[0].start = PFN_PHYS(vtl0_mem.start_pfn); pgmap->ranges[0].end = PFN_PHYS(vtl0_mem.last_pfn) - 1; pgmap->nr_range = 1; @@ -405,8 +408,11 @@ static int mshv_vtl_ioctl_add_vtl0_mem(struct mshv_vtl *vtl, void __user *arg) /* * Determine the highest page order that can be used for the given memory range. * This works best when the range is aligned; i.e. both the start and the length. + * Clamp to MAX_FOLIO_ORDER to avoid a WARN in memremap_pages() when the range + * alignment exceeds the maximum supported folio order for this kernel config. */ - pgmap->vmemmap_shift = count_trailing_zeros(vtl0_mem.start_pfn | vtl0_mem.last_pfn); + pgmap->vmemmap_shift = min(count_trailing_zeros(vtl0_mem.start_pfn | vtl0_mem.last_pfn), + MAX_FOLIO_ORDER); dev_dbg(vtl->module_dev, "Add VTL0 memory: start: 0x%llx, end_pfn: 0x%llx, page order: %lu\n", vtl0_mem.start_pfn, vtl0_mem.last_pfn, pgmap->vmemmap_shift); @@ -415,7 +421,7 @@ static int mshv_vtl_ioctl_add_vtl0_mem(struct mshv_vtl *vtl, void __user *arg) if (IS_ERR(addr)) { dev_err(vtl->module_dev, "devm_memremap_pages error: %ld\n", PTR_ERR(addr)); kfree(pgmap); - return -EFAULT; + return PTR_ERR(addr); } /* Don't free pgmap, since it has to stick around until the memory |