On Mon, Jun 24, 2024 at 11:42:44PM +0530, Nikunj A. Dadhania wrote: > Sure, here is the new patch. I have separated the variable name changes to a new patch. Right, please next time you send your set, sort the cleanups to sev-guest first so that I can pick them up separately. > > Subject: [PATCH] virt: sev-guest: Ensure the SNP guest messages do not exceed > a page > > Currently, snp_guest_msg includes a message header (96 bytes) and a > payload (4000 bytes). There is an implicit assumption here that the SNP > message header will always be 96 bytes, and with that assumption the > payload array size has been set to 4000 bytes magic number. If any new > member is added to the SNP message header, the SNP guest message will span > more than a page. > > Instead of using magic number '4000' for the payload, declare the > snp_guest_msg in a way that payload plus the message header do not exceed a > page. > > Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx> > Suggested-by: Tom Lendacky <thomas.lendacky@xxxxxxx> > --- > drivers/virt/coco/sev-guest/sev-guest.h | 2 +- > drivers/virt/coco/sev-guest/sev-guest.c | 3 +++ > 2 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/virt/coco/sev-guest/sev-guest.h b/drivers/virt/coco/sev-guest/sev-guest.h > index ceb798a404d6..de14a4f01b9d 100644 > --- a/drivers/virt/coco/sev-guest/sev-guest.h > +++ b/drivers/virt/coco/sev-guest/sev-guest.h > @@ -60,7 +60,7 @@ struct snp_guest_msg_hdr { > > struct snp_guest_msg { > struct snp_guest_msg_hdr hdr; > - u8 payload[4000]; > + u8 payload[PAGE_SIZE - sizeof(struct snp_guest_msg_hdr)]; > } __packed; > > #endif /* __VIRT_SEVGUEST_H__ */ > diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c > index 427571a2d1a2..c4aae5d4308e 100644 > --- a/drivers/virt/coco/sev-guest/sev-guest.c > +++ b/drivers/virt/coco/sev-guest/sev-guest.c > @@ -1033,6 +1033,9 @@ static int __init sev_guest_probe(struct platform_device *pdev) > snp_dev->dev = dev; > snp_dev->secrets = secrets; > > + /* Ensure SNP guest messages do not span more than a page */ > + BUILD_BUG_ON(sizeof(struct snp_guest_msg) > PAGE_SIZE); > + > /* Allocate the shared page used for the request and response message. */ > snp_dev->request = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); > if (!snp_dev->request) > -- Yap, that's exactly how stuff like that should be done: Acked-by: Borislav Petkov (AMD) <bp@xxxxxxxxx> -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette