On 12.01.2026 12:18, Andrew Cooper wrote: > On 12/01/2026 11:09 am, Jan Beulich wrote: >> On 09.01.2026 19:28, Petr Beneš wrote: >>> From: Petr Beneš <[email protected]> >>> >>> Commit 7e5b662 fixed p2m_altp2m_get_or_propagate() to use the altp2m's >>> default_access when propagating entries from the host p2m. However, the same >>> fix was not applied to altp2m_get_effective_entry(), which has the same >>> issue. >>> >>> When altp2m_get_effective_entry() prepopulates a superpage from the host >>> p2m, it incorrectly uses the host p2m's access permissions instead of >>> the altp2m's default_access. This causes problems when the superpage is >>> later split (e.g., when setting mem_access on a specific 4K page): all >>> 512 entries inherit the host p2m's access rights instead of the altp2m's >>> default_access. >>> >>> This issue became apparent after commit 50baf2d, which causes the host p2m >>> to use superpages more frequently. Before that commit, the host p2m >>> typically had 4K entries after VM restore, so the prepopulate branch was >>> rarely taken. >>> >>> Symptoms include memory-access events firing for unexpected pages when >>> using VMI tools with altp2m, particularly after VM resume. >>> The issue can be worked around by booting with "hap_1gb=0 hap_2mb=0". >>> >>> Fixes: 7e5b662 ("x86/altp2m: p2m_altp2m_get_or_propagate() should honor >>> ap2m->default_access") >> You didn't even Cc Tamas, who I think once again will need to ack this. >> Already with the referenced change I didn't quite understand the >> reasoning. >> >> However, two formal points: Please use 12-digit hashes, as demanded by >> sending-patches.pandoc. Plus I don't think Fixes: is quite right here. >> That earlier change of yours didn't mean to do more than it did, by its >> title and description. We relatively recently introduced Amends:, which >> may be a suitable fit here. > > I beg your pardon? Fixes are and Amends are synonyms.
This is news to me. To me a "fix" addresses a bug in the referenced commit. Whereas making a related change which isn't strictly a bugfix to the referenced earlier change is what Amends: was introduced for. If both were synonyms, why would you not have objected to the introduction of Amends:? > You cannot use > them like this, and you absolutely cannot expect contributors to know > your personal interpretation of the words. "My personal interpretation of the words" has become the community's with the committing of the change introducing Amends:. And I think I can expect contributors to read sending-patches.pandoc? Jan
