From: Joerg Roedel <jroedel@suse.de>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Joerg Roedel <joro@8bytes.org>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"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 v2 3/5] x86/boot/compressed/64: Check SEV encryption in 64-bit boot-path
Date: Tue, 20 Oct 2020 17:48:12 +0200 [thread overview]
Message-ID: <20201020154812.GB22179@suse.de> (raw)
In-Reply-To: <20201020141259.GC2996696@rani.riverdale.lan>
On Tue, Oct 20, 2020 at 10:12:59AM -0400, Arvind Sankar wrote:
> On Tue, Oct 20, 2020 at 02:18:54PM +0200, Joerg Roedel wrote:
> Why use r10-r12 rather than the caller-save registers? Even for the head
> code where you need to perserve the cr3 value you can just return it in
> rax?
It can surely be optimized, but it makes the code less robust. This
function is only called from assembly so the standard x86-64 calling
conventions might not be followed strictly. I think its better to make
as few assumptions as possible about the calling code to avoid
regressions. Changes to the head code are not necessarily tested with
SEV/SEV-ES guests by developers.
Regards,
Joerg
next prev parent reply other threads:[~2020-10-20 15:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 12:18 [PATCH v2 0/5] x86/sev-es: Mitigate some HV attack vectors Joerg Roedel
2020-10-20 12:18 ` [PATCH v2 1/5] x86/boot/compressed/64: Introduce sev_status Joerg Roedel
2020-10-20 12:18 ` [PATCH v2 2/5] x86/boot/compressed/64: Add CPUID sanity check to early #VC handler Joerg Roedel
2020-10-20 12:18 ` [PATCH v2 3/5] x86/boot/compressed/64: Check SEV encryption in 64-bit boot-path Joerg Roedel
2020-10-20 14:12 ` Arvind Sankar
2020-10-20 15:48 ` Joerg Roedel [this message]
2020-10-20 16:04 ` Arvind Sankar
2020-10-21 12:49 ` Joerg Roedel
2020-10-20 12:18 ` [PATCH v2 4/5] x86/head/64: Check SEV encryption before switching to kernel page-table Joerg Roedel
2020-10-20 12:18 ` [PATCH v2 5/5] x86/sev-es: Do not support MMIO to/from encrypted memory Joerg Roedel
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