On 10/16/23 15:27, Michael Roth wrote:
From: Brijesh Singh <brijesh.singh@xxxxxxx> Implement a workaround for an SNP erratum where the CPU will incorrectly signal an RMP violation #PF if a hugepage (2mb or 1gb) collides with the RMP entry of a VMCB, VMSA or AVIC backing page. When SEV-SNP is globally enabled, the CPU marks the VMCB, VMSA, and AVIC backing pages as "in-use" via a reserved bit in the corresponding RMP entry after a successful VMRUN. This is done for _all_ VMs, not just SNP-Active VMs. If the hypervisor accesses an in-use page through a writable translation, the CPU will throw an RMP violation #PF. On early SNP hardware, if an in-use page is 2mb aligned and software accesses any part of the associated 2mb region with a hupage, the CPU will incorrectly treat the entire 2mb region as in-use and signal a spurious RMP violation #PF.
I don't understand if this can happen even if SEV-SNP is not in use, just because it is supported on the host? If so, should this be Cc'd to stable? (I can tweak the wording and submit it).
Paolo
