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Peter Anvin" , virtualization@lists.linux.dev, bcm-kernel-feedback-list@broadcom.com, linux-kernel@vger.kernel.org, Christoph Lameter , Andrew Morton , Tom Lendacky , Bo Gan , linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-coco@lists.linux.dev, kvm@vger.kernel.org, Zack Rusin Subject: [PATCH v1 0/2] x86/vmware: Share steal-time storage in encrypted guests Date: Wed, 16 Sep 2026 01:05:38 -0400 Message-ID: X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-DetectorID-Processed: b00c1d49-9d2e-4205-b15f-d015386d3d5e VMware registers each per-CPU steal-time GPA with the host. An encrypted guest must first convert that storage to shared memory, but the existing setup publishes the address without conversion. Patch 1 makes the decrypted per-CPU section available with CONFIG_X86_MEM_ENCRYPT, including TDX-only configurations. Patch 2 defers encrypted-guest setup until allocator-backed page-table splitting is available, converts every possible CPU's storage before publishing any GPA, and attempts to roll back all conversions on failure. TDX's conversion callback uses __pa(), so patch 2 preflights every possible CPU and leaves steal time disabled if a TDX guest uses vmalloc-backed per-CPU storage. This covers percpu_alloc=page and automatic allocator fallback. AMD encrypted guests support those mappings and are not rejected. Supporting them in TDX would require a separate conversion-API change. Conversion need not preserve zeroes, and the host initializes only the 8-byte counter. Patch 2 therefore clears each 64-byte object after conversion and before registration, without disturbing other decrypted objects that can share its page. The intended merge path is tip's x86/vmware branch, following commit ac26963a1175 ("percpu: Introduce DEFINE_PER_CPU_DECRYPTED"). Per-CPU and asm-generic maintainer Acks are requested for patch 1. This replaces patch 4 of Alexey's v2 posting: https://lore.kernel.org/all/20260309235250.2611115-1-alexey.makhalov@broadcom.com/ Zack Rusin (2): percpu: Use X86_MEM_ENCRYPT for decrypted per-CPU data x86/vmware: Decrypt steal-time storage before sharing it arch/x86/kernel/cpu/vmware.c | 96 ++++++++++++++++++++++++++++++- include/asm-generic/vmlinux.lds.h | 2 +- include/linux/percpu-defs.h | 2 +- 3 files changed, 97 insertions(+), 3 deletions(-) base-commit: fd73f4a6659897191fa0d40695fe370925dd3780 -- 2.53.0