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[144.49.247.125]) by smtp-relay.gmail.com with ESMTPS id 71dfb90a1353d-5c9a524df98sm1578614e0c.3.2026.09.17.16.07.56 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 17 Sep 2026 16:07:56 -0700 (PDT) X-Relaying-Domain: broadcom.com X-CFilter-Loop: Reflected Received: by mail-pg1-f198.google.com with SMTP id 41be03b00d2f7-cc4e496e5c3so55235a12.0 for ; Thu, 17 Sep 2026 16:07:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; t=1789686475; x=1790291275; darn=lists.linux.dev; h=content-transfer-encoding:content-type:in-reply-to:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:from:to:cc:subject:date:message-id:reply-to:content-type; bh=KkBkFvNjZkmBQ+ciR5KjrTSHBNZ+IYK3WHfHxYYYMK8=; b=ZIOfmENoyHAtAHpc8jvCgMRgnSKHdMSnmRahUNYFdZtXbKkCmej0+P+GXnpEXcW/Iu RRJyOGFp+hGfz5EODAfR4a4aruBz3yxaOixIR0mlfNYqyseDS6SMB3IIck/ft5jbFter Ub62w2rCjDBMTSbwToWSQfEPx7mTFWunlp6to= X-Forwarded-Encrypted: i=1; AKwUvBxStJNSw5/r/CUvwZ/QiA0cZNUtPd1re+iAdkWrVAt+L6Nf4PVyyJdIkBvhvOjKnc7gV8Jb7VDG72Q/s0h1ig==@lists.linux.dev X-Received: by 2002:a17:90b:1e04:b0:39e:4c80:f680 with SMTP id 98e67ed59e1d1-39e54f3dba9mr1123049a91.31.1789686474961; Thu, 17 Sep 2026 16:07:54 -0700 (PDT) X-Received: by 2002:a17:90b:1e04:b0:39e:4c80:f680 with SMTP id 98e67ed59e1d1-39e54f3dba9mr1122991a91.31.1789686474393; Thu, 17 Sep 2026 16:07:54 -0700 (PDT) Received: from [10.211.247.235] ([216.221.25.44]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-33bf596e1f6sm21060020eec.1.2026.09.17.16.07.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Sep 2026 16:07:54 -0700 (PDT) Message-ID: <58026818-7737-4560-be64-5cf22f2d8d69@broadcom.com> Date: Thu, 17 Sep 2026 16:07:56 -0700 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 0/4] x86/vmware: Preserve panic diagnostics in vmware.log To: Zack Rusin , Borislav Petkov , Ajay Kaher , Alexey Makhalov , x86@kernel.org, Petr Mladek , Joel Granados , Baoquan He Cc: Thomas Gleixner , Ingo Molnar , Dave Hansen , "H . Peter Anvin" , virtualization@lists.linux.dev, bcm-kernel-feedback-list@broadcom.com, linux-kernel@vger.kernel.org, John Ogness , Steven Rostedt , Sergey Senozhatsky , Kees Cook , Andrew Morton , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Dave Young , Jonathan Corbet , Bo Gan , Brennan Lamoreaux , kexec@lists.infradead.org, linux-doc@vger.kernel.org References: From: Maaz Mombasawala Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-DetectorID-Processed: b00c1d49-9d2e-4205-b15f-d015386d3d5e On 9/8/26 11:07 AM, Zack Rusin wrote: > A virtual machine may have neither guest-local persistent storage nor > working userspace after a panic. The host's vmware.log remains available > after the VM terminates, and a production encrypted guest is the only > component able to export readable panic text. Hyper-V already provides > this class of host-persistent panic reporting. > > Add a panic-only VMware logger that copies the newest 4 KiB of the kernel > log and sends it with bounded low-bandwidth RPC work. Ordinary guests > enable text transfer by default; encrypted guests require an administrator > to opt in through kernel.vmware_record_panic_msg. A separate late dumper > reports the structured crash event after built-in dumpers and suppresses > the event while a crash kernel is loaded, because a configured VMware host > may terminate the VM before the reporting hypercall returns. > > Patch 4 makes panic diagnostics run before kdump by default on VMware > guests. This follows existing platform uses of > crash_kexec_post_notifiers, with Hyper-V as the closest guest-reporting > precedent. Unlike Hyper-V, VMware exposes no capability bit for this > behavior. An explicit crash_kexec_post_notifiers=0 still wins, and patch 4 > can be dropped without affecting patches 1 through 3. > > This replaces patches 2 and 3 of Alexey's v2 posting: > https://lore.kernel.org/all/20260309235250.2611115-1-alexey.makhalov@broadcom.com/ > > The intended merge path is tip's x86/vmware branch. Boris please review the > VMware transport and policy. Petr and John, please review the panic-only > dumper use and registration ordering. Joel and Kees, please review the > sysctl. Baoquan and the KEXEC/KDUMP team, please review the > loaded-crash-kernel guard and the default in patch 4. > > Zack Rusin (4): > x86/vmware: Add a bounded panic log sender > x86/vmware: Add the vmware_record_panic_msg sysctl > x86/vmware: Report guest crashes after kmsg dumpers > x86/vmware: Run panic diagnostics before kdump by default > > Documentation/admin-guide/sysctl/kernel.rst | 14 ++ > arch/x86/include/asm/vmware.h | 2 + > arch/x86/kernel/cpu/vmware.c | 245 ++++++++++++++++++++ > 3 files changed, 261 insertions(+) > > > base-commit: cee9395acd8043be0644b25c34bfa86623f2b935 LGTM for the series Reviewed-by: Maaz Mombasawala -- Maaz Mombasawala