From: Sean Christopherson <seanjc@google.com>
To: Ackerley Tng <ackerleytng@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Kiryl Shutsemau <kas@kernel.org>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Vishal Annapurve <vannapurve@google.com>,
Yan Zhao <yan.y.zhao@intel.com>,
Michael Roth <michael.roth@amd.com>,
Isaku Yamahata <isaku.yamahata@intel.com>,
Chao Peng <chao.p.peng@linux.intel.com>,
Xiaoyao Li <xiaoyao.li@intel.com>,
Zongyao Chen <ZongYao.Chen@linux.alibaba.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-coco@lists.linux.dev,
Yu Zhang <yu.c.zhang@linux.intel.com>,
Fuad Tabba <tabba@google.com>
Subject: Re: [PATCH v2 4/5] KVM: SNP: Fix kunmap_local() unmapping order
Date: Tue, 26 May 2026 08:55:49 -0700 [thread overview]
Message-ID: <ahXChYgryPiOck1L@google.com> (raw)
In-Reply-To: <20260522-fix-sev-gmem-post-populate-v2-4-3f196bfad5a1@google.com>
Similar comment on the shortlog as patch two. "Fix the order" tells the reader
nothing useful, other than the author of the patch thought there was a bug.
KVM: SEV: Unmap local kmaps in LIFO order, per highmem requirements
No need for a new version, I'll massage when applying.
On Fri, May 22, 2026, Ackerley Tng wrote:
> Mappings created with kmap_local_page() or kmap_local_pfn() must be
> unmapped in the reverse order they were acquired, following a LIFO
> (last-in, first-out) stack-based approach.
>
> In sev_gmem_post_populate(), src_vaddr is mapped first and dst_vaddr is
> mapped second. The current code incorrectly calls kunmap_local() for
> src_vaddr before dst_vaddr.
>
> Swap the kunmap_local() calls to ensure the mappings are released in the
> correct order.
It's worth calling out that this is completely benign since SNP is 64-bit only.
next prev parent reply other threads:[~2026-05-26 15:55 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-22 22:46 [PATCH v2 0/5] guest_memfd fixes for bind and populate Ackerley Tng via B4 Relay
2026-05-22 22:46 ` Ackerley Tng
2026-05-22 22:46 ` [PATCH v2 1/5] KVM: guest_memfd: Use write permissions when GUP-ing source pages Ackerley Tng via B4 Relay
2026-05-22 22:46 ` Ackerley Tng
2026-05-22 23:47 ` sashiko-bot
2026-05-26 16:13 ` Sean Christopherson
2026-05-22 22:46 ` [PATCH v2 2/5] KVM: guest_memfd: Fix possible signed integer overflow Ackerley Tng via B4 Relay
2026-05-22 22:46 ` Ackerley Tng
2026-05-26 15:53 ` Sean Christopherson
2026-05-27 18:26 ` Ackerley Tng
2026-05-27 19:26 ` Sean Christopherson
2026-05-27 20:17 ` Ackerley Tng
2026-05-27 22:08 ` Sean Christopherson
2026-05-22 22:46 ` [PATCH v2 3/5] KVM: guest_memfd: Handle errors from xa_store_range() when binding Ackerley Tng via B4 Relay
2026-05-22 22:46 ` Ackerley Tng
2026-05-26 16:39 ` Sean Christopherson
2026-05-27 19:11 ` Ackerley Tng
2026-05-27 22:43 ` Sean Christopherson
2026-05-22 22:46 ` [PATCH v2 4/5] KVM: SNP: Fix kunmap_local() unmapping order Ackerley Tng via B4 Relay
2026-05-22 22:46 ` Ackerley Tng
2026-05-26 15:55 ` Sean Christopherson [this message]
2026-05-22 22:46 ` [PATCH v2 5/5] KVM: SNP: Mark source page dirty in sev_gmem_post_populate Ackerley Tng via B4 Relay
2026-05-22 22:46 ` Ackerley Tng
2026-05-26 16:47 ` Sean Christopherson
2026-05-27 19:14 ` Ackerley Tng
2026-05-26 16:55 ` [PATCH v2 0/5] guest_memfd fixes for bind and populate Sean Christopherson
2026-05-27 18:19 ` Sean Christopherson
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