From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.skyhub.de ([5.9.137.197]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mhxPt-002TdX-Kp for kexec@lists.infradead.org; Tue, 02 Nov 2021 17:17:48 +0000 Date: Tue, 2 Nov 2021 18:17:39 +0100 From: Borislav Petkov Subject: Re: [PATCH v2 01/12] kexec: Allow architecture code to opt-out at runtime Message-ID: References: <20210913155603.28383-1-joro@8bytes.org> <20210913155603.28383-2-joro@8bytes.org> <87pmrjbmy9.fsf@disp2133> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87pmrjbmy9.fsf@disp2133> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: "Eric W. Biederman" Cc: Joerg Roedel , x86@kernel.org, kexec@lists.infradead.org, Joerg Roedel , stable@vger.kernel.org, hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Sean Christopherson , Martin Radev , Arvind Sankar , linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org 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. Well, the executive summary is that you have a guest whose memory *and* registers are encrypted so the hypervisor cannot have a poke inside and reset the vCPU like it would normally do. So you need to do that dance differently, i.e, the patchset. If you try to kexec such a guest now, it'll init only the BSP, as Joerg said. So I guess a single-threaded kdump. And yes, one of the prominent use cases is kdumping from such a guest, as distros love doing kdump for debugging. I hope that explains it better. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec