On Mon, Feb 02, 2026 at 08:51:01AM -0800, [email protected] wrote: > From: Michael Kelley <[email protected]> > > Huge page mappings in the guest physical address space depend on having > matching alignment of the userspace address in the parent partition and > of the guest physical address. Add a comment that captures this > information. See the link to the mailing list thread. > > No code or functional change. > > Link: > https://lore.kernel.org/linux-hyperv/[email protected]/T/#m0871d2cae9b297fd397ddb8459e534981307c7dc > Signed-off-by: Michael Kelley <[email protected]> > --- > drivers/hv/mshv_root_main.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c > index 681b58154d5e..bc738ff4508e 100644 > --- a/drivers/hv/mshv_root_main.c > +++ b/drivers/hv/mshv_root_main.c > @@ -1389,6 +1389,20 @@ mshv_partition_ioctl_set_memory(struct mshv_partition > *partition, > if (mem.flags & BIT(MSHV_SET_MEM_BIT_UNMAP)) > return mshv_unmap_user_memory(partition, mem); > > + /* > + * If the userspace_addr and the guest physical address (as derived > + * from the guest_pfn) have the same alignment modulo PMD huge page > + * size, the MSHV driver can map any PMD huge pages to the guest > + * physical address space as PMD huge pages. If the alignments do > + * not match, PMD huge pages must be mapped as single pages in the > + * guest physical address space. The MSHV driver does not enforce > + * that the alignments match, and it invokes the hypervisor to set > + * up correct functional mappings either way. See mshv_chunk_stride(). > + * The caller of the ioctl is responsible for providing userspace_addr > + * and guest_pfn values with matching alignments if it wants the guest > + * to get the performance benefits of PMD huge page mappings of its > + * physical address space to real system memory. > + */
Thanks. However, I'd suggest to reduce this commet a lot and put the details into the commit message instead. Also, why this place? Why not a part of the function description instead, for example? Thanks, Stanislav > return mshv_map_user_memory(partition, mem); > } > > -- > 2.25.1
