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From: Joerg Roedel <jroedel@suse.de>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Borislav Petkov <bp@alien8.de>, Joerg Roedel <joro@8bytes.org>,
	x86@kernel.org, kexec@lists.infradead.org,
	stable@vger.kernel.org, hpa@zytor.com,
	Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Jiri Slaby <jslaby@suse.cz>,
	Dan Williams <dan.j.williams@intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Juergen Gross <jgross@suse.com>,
	Kees Cook <keescook@chromium.org>,
	David Rientjes <rientjes@google.com>,
	Cfir Cohen <cfir@google.com>, Erdem Aktas <erdemaktas@google.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mike Stunes <mstunes@vmware.com>,
	Sean Christopherson <seanjc@google.com>,
	Martin Radev <martin.b.radev@gmail.com>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v2 01/12] kexec: Allow architecture code to opt-out at runtime
Date: Tue, 2 Nov 2021 18:00:21 +0100	[thread overview]
Message-ID: <YYFupTJjUljpuZgL@suse.de> (raw)
In-Reply-To: <87pmrjbmy9.fsf@disp2133>

Hi again,

On Mon, Nov 01, 2021 at 04:11:42PM -0500, Eric W. Biederman wrote:
> I seem to remember the consensus when this was reviewed that it was
> unnecessary and there is already support for doing something like
> this at a more fine grained level so we don't need a new kexec hook.

Forgot to state to problem again which these patches solve:

Currently a Linux kernel running as an SEV-ES guest has no way to
successfully kexec into a new kernel. The normal SIPI sequence to reset
the non-boot VCPUs does not work in SEV-ES guests and special code is
needed in Linux to safely hand over the VCPUs from one kernel to the
next. What happens currently is that the kexec'ed kernel will just hang.

The code which implements the VCPU hand-over is also included in this
patch-set, but it requires a certain level of Hypervisor support which
is not available everywhere.

To make it clear to the user that kexec will not work in their
environment, it is best to disable the respected syscalls. This is what
the hook is needed for.

Regards,

-- 
Jörg Rödel
jroedel@suse.de

SUSE Software Solutions Germany GmbH
Maxfeldstr. 5
90409 Nürnberg
Germany
 
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev


  parent reply	other threads:[~2021-11-02 17:00 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-13 15:55 [PATCH v2 00/12] x86/sev: KEXEC/KDUMP support for SEV-ES guests Joerg Roedel
2021-09-13 15:55 ` [PATCH v2 01/12] kexec: Allow architecture code to opt-out at runtime Joerg Roedel
2021-11-01 16:10   ` Borislav Petkov
2021-11-01 21:11     ` Eric W. Biederman
2021-11-02 16:37       ` Joerg Roedel
2021-11-02 17:00       ` Joerg Roedel [this message]
2021-11-02 18:17         ` Eric W. Biederman
2021-11-02 17:17       ` Borislav Petkov
2021-09-13 15:55 ` [PATCH v2 02/12] x86/kexec/64: Forbid kexec when running as an SEV-ES guest Joerg Roedel
2021-09-13 15:55 ` [PATCH v2 03/12] x86/sev: Save and print negotiated GHCB protocol version Joerg Roedel
2021-11-03 14:27   ` Borislav Petkov
2021-09-13 15:55 ` [PATCH v2 04/12] x86/sev: Do not hardcode " Joerg Roedel
2021-09-13 15:55 ` [PATCH v2 05/12] x86/sev: Use GHCB protocol version 2 if supported Joerg Roedel
2021-11-03 16:05   ` Borislav Petkov
2021-09-13 15:55 ` [PATCH v2 06/12] x86/sev: Cache AP Jump Table Address Joerg Roedel
2021-11-08 18:14   ` Borislav Petkov
2021-09-13 15:55 ` [PATCH v2 07/12] x86/sev: Setup code to park APs in the AP Jump Table Joerg Roedel
2021-11-10 16:37   ` Borislav Petkov
2021-09-13 15:55 ` [PATCH v2 08/12] x86/sev: Park APs on AP Jump Table with GHCB protocol version 2 Joerg Roedel
2021-11-12 16:33   ` Borislav Petkov
2021-09-13 15:56 ` [PATCH v2 09/12] x86/sev: Use AP Jump Table blob to stop CPU Joerg Roedel
2021-11-15 18:44   ` Borislav Petkov
2021-09-13 15:56 ` [PATCH v2 10/12] x86/sev: Add MMIO handling support to boot/compressed/ code Joerg Roedel
2021-09-13 15:56 ` [PATCH v2 11/12] x86/sev: Handle CLFLUSH MMIO events Joerg Roedel
2021-09-13 15:56 ` [PATCH v2 12/12] x86/sev: Support kexec under SEV-ES with AP Jump Table blob Joerg Roedel
2021-09-13 16:02 ` [PATCH v2 00/12] x86/sev: KEXEC/KDUMP support for SEV-ES guests Dave Hansen
2021-09-13 16:14   ` Joerg Roedel
2021-09-13 16:21     ` Dave Hansen

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