From: Joerg Roedel <jroedel@suse.de>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Joerg Roedel <joro@8bytes.org>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Kees Cook <keescook@chromium.org>,
Martin Radev <martin.b.radev@gmail.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/5] x86/boot/compressed/64: Introduce sev_status
Date: Wed, 28 Oct 2020 17:55:43 +0100 [thread overview]
Message-ID: <20201028165543.GL22179@suse.de> (raw)
In-Reply-To: <20201028165007.GB1989568@rani.riverdale.lan>
On Wed, Oct 28, 2020 at 12:50:07PM -0400, Arvind Sankar wrote:
> On Wed, Oct 28, 2020 at 09:23:52AM +0100, Joerg Roedel wrote:
> > On Mon, Oct 26, 2020 at 07:27:06PM +0100, Borislav Petkov wrote:
> > > A couple of lines above you call get_sev_encryption_bit() which already
> > > reads MSR_AMD64_SEV. Why not set sev_status there too instead of reading
> > > that MSR again here?
> > >
> > > It can read that MSR once and use sev_status(%rip) from then on to avoid
> > > reading that MSR multiple times...
> >
> > Right, makes sense. I updated the patch.
>
> Hang on, get_sev_encryption_bit() is also called from startup_32(),
> so it can't contain any 64-bit instructions to set sev_status.
Yeah, figured that out too and discussed it with Boris. Decided to leave
it as-is and add a comment why the MSR is re-read.
Thanks,
Joerg
next prev parent reply other threads:[~2020-10-29 2:45 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-21 12:39 [PATCH v3 0/5] x86/sev-es: Mitigate some HV attack vectors Joerg Roedel
2020-10-21 12:39 ` [PATCH v3 1/5] x86/boot/compressed/64: Introduce sev_status Joerg Roedel
2020-10-26 18:27 ` Borislav Petkov
2020-10-28 8:23 ` Joerg Roedel
2020-10-28 16:50 ` Arvind Sankar
2020-10-28 16:55 ` Joerg Roedel [this message]
2020-10-21 12:39 ` [PATCH v3 2/5] x86/boot/compressed/64: Add CPUID sanity check to early #VC handler Joerg Roedel
2020-10-27 10:38 ` Borislav Petkov
2020-10-28 8:31 ` Joerg Roedel
2020-10-21 12:39 ` [PATCH v3 3/5] x86/boot/compressed/64: Check SEV encryption in 64-bit boot-path Joerg Roedel
2020-10-27 11:08 ` Borislav Petkov
2020-10-28 8:38 ` Joerg Roedel
2020-10-27 11:09 ` Borislav Petkov
2020-10-21 12:39 ` [PATCH v3 4/5] x86/head/64: Check SEV encryption before switching to kernel page-table Joerg Roedel
2020-10-27 11:20 ` Borislav Petkov
2020-10-21 12:39 ` [PATCH v3 5/5] x86/sev-es: Do not support MMIO to/from encrypted memory Joerg Roedel
2020-10-27 11:26 ` Borislav Petkov
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