Messages in this thread | | | Date | Tue, 31 Jan 2023 15:53:39 +0000 | From | Sean Christopherson <> | Subject | Re: [Question PATCH kernel] x86/amd/sev/nmi+vc: Fix stack handling (why is this happening?) |
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On Tue, Jan 31, 2023, Joerg Roedel wrote: > On Mon, Jan 30, 2023 at 09:30:38AM -0800, H. Peter Anvin wrote: > > It's somewhat odd to me that reading %dr7 is volatile, but %dr6 is > > not... %dr6 is the status register! > > The reason is that on SEV-ES only accesses to DR7 will cause #VC > exceptions, DR0-DR6 are not intercepted.
I don't think that is technically true. A _well-behaved_ hypervisor will not intercept DR0-DR6 accesses for SEV-ES guests, but AFAICT nothing in the SEV-ES architecture enforces that behavior.
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