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| author | Alexey Kardashevskiy <[email protected]> | 2025-06-11 04:08:41 +0000 |
|---|---|---|
| committer | Borislav Petkov (AMD) <[email protected]> | 2025-06-18 20:55:53 +0000 |
| commit | 7ffeb2fc26707f613685ce7711c26a9de5890ab1 (patch) | |
| tree | 8e1477460058619a4c0e9d6cd7ba16591b80a56a | |
| parent | x86/sev: Allocate request in TSC_INFO_REQ on stack (diff) | |
| download | kernel-7ffeb2fc26707f613685ce7711c26a9de5890ab1.tar.gz kernel-7ffeb2fc26707f613685ce7711c26a9de5890ab1.zip | |
x86/sev: Document requirement for linear mapping of guest request buffers
The Guest Request supports 3 types of messages now, the largest is the
extended variant of MSG_REPORT_REQ: sizeof(snp_ext_report_req)==112. These
used to be allocated on stack and then moved to the SNP guest platform device
(snp_guest_dev) for the reason explained in
db10cb9b5746 ("virt: sevguest: Fix passing a stack buffer as a scatterlist target"):
aesgcm_encrypt() and aesgcm_decrypt() are used for guest messages and might
potentially use a crypto accelerator which requires DMA buffers to be in the
linear mapping.
Add a comment, warn and return an error when the buffers are not in linear
mapping.
Signed-off-by: Alexey Kardashevskiy <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Reviewed-by: Tom Lendacky <[email protected]>
Reviewed-by: Dionna Glaze <[email protected]>
Link: https://lore.kernel.org/[email protected]
| -rw-r--r-- | arch/x86/coco/sev/core.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index 068653865bfb..b0d423a353ab 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -2008,6 +2008,15 @@ int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req u64 seqno; int rc; + /* + * enc_payload() calls aesgcm_encrypt(), which can potentially offload to HW. + * The offload's DMA SG list of data to encrypt has to be in linear mapping. + */ + if (!virt_addr_valid(req->req_buf) || !virt_addr_valid(req->resp_buf)) { + pr_warn("AES-GSM buffers must be in linear mapping"); + return -EINVAL; + } + guard(mutex)(&snp_cmd_mutex); /* Check if the VMPCK is not empty */ |