From: Sean Christopherson <seanjc@google.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
Alexey Kardashevskiy <aik@amd.com>,
Peter Zijlstra <peterz@infradead.org>,
kvm@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Jiri Kosina <jkosina@suse.cz>, Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Borislav Petkov <bp@alien8.de>,
Tom Lendacky <thomas.lendacky@amd.com>
Subject: Re: [Question PATCH kernel] x86/amd/sev/nmi+vc: Fix stack handling (why is this happening?)
Date: Tue, 31 Jan 2023 16:47:20 +0000 [thread overview]
Message-ID: <Y9lGGLWovbh4v3Oy@google.com> (raw)
In-Reply-To: <Y9k7HUA85bZKCEVn@8bytes.org>
On Tue, Jan 31, 2023, Joerg Roedel wrote:
> On Tue, Jan 31, 2023 at 03:53:39PM +0000, Sean Christopherson wrote:
> > 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.
>
> Not from the hardware architecture side, but the GHCB spec does not
> list NAE events for DR0-DR6 accesses, so a guest is not required to
> handle them in the VC handler.
>
> Linux under SEV-ES will crash if the HV intercepts debug registers,
> except DR7.
Right, I'm just objecting to the wording of "DR0-DR6 are not intercepted". E.g.
from a security perspective, the kernel shouldn't rely on DR0-DR6 to execute
cleanly.
next prev parent reply other threads:[~2023-01-31 16:47 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-27 3:56 [Question PATCH kernel] x86/amd/sev/nmi+vc: Fix stack handling (why is this happening?) Alexey Kardashevskiy
2023-01-27 9:08 ` Peter Zijlstra
2023-01-27 10:37 ` Joerg Roedel
2023-01-27 11:56 ` Alexey Kardashevskiy
2023-01-27 12:59 ` Joerg Roedel
2023-01-27 17:25 ` Joerg Roedel
2023-01-28 11:24 ` Alexey Kardashevskiy
2023-01-28 13:52 ` Joerg Roedel
2023-01-30 9:17 ` Joerg Roedel
2023-01-30 17:30 ` H. Peter Anvin
2023-01-30 18:04 ` Borislav Petkov
2023-01-31 8:57 ` Joerg Roedel
2023-01-31 15:53 ` Sean Christopherson
2023-01-31 16:00 ` Joerg Roedel
2023-01-31 16:47 ` Sean Christopherson [this message]
2023-01-27 12:13 ` Alexey Kardashevskiy
2023-01-27 12:41 ` Peter Zijlstra
2023-01-31 10:37 ` [tip: x86/urgent] x86/debug: Fix stack recursion caused by wrongly ordered DR7 accesses tip-bot2 for Joerg Roedel
2023-01-31 11:57 ` tip-bot2 for Joerg Roedel
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