From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C13D42F261C; Wed, 28 Jan 2026 15:51:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769615509; cv=none; b=ogaZXgGVoZJv2NT8l/PLWeA7BHvtBntsMwqRwlF78c8lQbIiukF/cAnagixkE2hmo/HZHeC14hzJN7oUB7VFhXd2d0/m1YjgFRR8ui+KbAkZNCFb4jv4KQloV4OsAI2j0hs3svCLDMzO92GPTBvYVllv2nHeFnm05RYsOQf62xo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769615509; c=relaxed/simple; bh=q16z+j2KwHdG7oVg/VUImNR4wEF9j8UmfT4NS9bNK2s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RYKaRSdJTzTzNp8P9RbLoWKD2Cpw7924nR/X+GU1Lv4sX2Z2t55qJYScu08khfWIB6bO/M/e0FPnsL7eVzJyoXfdgXL65FO5vsQ9vmPdR2KXSZay/n8ndRmSggFYYPNwc7BlopcwbAyCxIschNj2DRjabfLDAQin/PUl2FpcfMQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=eTI+otmb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="eTI+otmb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4BF88C4CEF1; Wed, 28 Jan 2026 15:51:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1769615509; bh=q16z+j2KwHdG7oVg/VUImNR4wEF9j8UmfT4NS9bNK2s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eTI+otmbIVaKqZXySZuWEtcvNMBsgfi1J4RYkv5tKePKpzlbB0Rh6J9t1bUp+YiP9 G7/jq+3cUisaQBby6xR2nFSbb4cvlSSctprR7iEqWG+flsAVxSssPbJGCNilFwBFhN h3qjZtglfj/djFfEiSlmvvjc4TNXEO9D3PdprOg0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, kernel test robot , Dan Carpenter , Michael Kelley , Roman Kisel , Wei Liu , Sasha Levin Subject: [PATCH 6.18 006/227] Drivers: hv: Always do Hyper-V panic notification in hv_kmsg_dump() Date: Wed, 28 Jan 2026 16:20:51 +0100 Message-ID: <20260128145344.568009889@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260128145344.331957407@linuxfoundation.org> References: <20260128145344.331957407@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael Kelley [ Upstream commit 49f49d47af67f8a7b221db1d758fc634242dc91a ] hv_kmsg_dump() currently skips the panic notification entirely if it doesn't get any message bytes to pass to Hyper-V due to an error from kmsg_dump_get_buffer(). Skipping the notification is undesirable because it leaves the Hyper-V host uncertain about the state of a panic'ed guest. Fix this by always doing the panic notification, even if bytes_written is zero. Also ensure that bytes_written is initialized, which fixes a kernel test robot warning. The warning is actually bogus because kmsg_dump_get_buffer() happens to set bytes_written even if it fails, and in the kernel test robot's CONFIG_PRINTK not set case, hv_kmsg_dump() is never called. But do the initialization for robustness and to quiet the static checker. Fixes: 9c318a1d9b50 ("Drivers: hv: move panic report code from vmbus to hv early init code") Reported-by: kernel test robot Reported-by: Dan Carpenter Closes: https://lore.kernel.org/all/202512172103.OcUspn1Z-lkp@intel.com/ Signed-off-by: Michael Kelley Reviewed-by: Roman Kisel Signed-off-by: Wei Liu Signed-off-by: Sasha Levin --- drivers/hv/hv_common.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c index e109a620c83fc..71fd3ea4fa8bd 100644 --- a/drivers/hv/hv_common.c +++ b/drivers/hv/hv_common.c @@ -195,13 +195,15 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper, /* * Write dump contents to the page. No need to synchronize; panic should - * be single-threaded. + * be single-threaded. Ignore failures from kmsg_dump_get_buffer() since + * panic notification should be done even if there is no message data. + * Don't assume bytes_written is set in case of failure, so initialize it. */ kmsg_dump_rewind(&iter); - kmsg_dump_get_buffer(&iter, false, hv_panic_page, HV_HYP_PAGE_SIZE, + bytes_written = 0; + (void)kmsg_dump_get_buffer(&iter, false, hv_panic_page, HV_HYP_PAGE_SIZE, &bytes_written); - if (!bytes_written) - return; + /* * P3 to contain the physical address of the panic page & P4 to * contain the size of the panic data in that page. Rest of the @@ -210,7 +212,7 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper, hv_set_msr(HV_MSR_CRASH_P0, 0); hv_set_msr(HV_MSR_CRASH_P1, 0); hv_set_msr(HV_MSR_CRASH_P2, 0); - hv_set_msr(HV_MSR_CRASH_P3, virt_to_phys(hv_panic_page)); + hv_set_msr(HV_MSR_CRASH_P3, bytes_written ? virt_to_phys(hv_panic_page) : 0); hv_set_msr(HV_MSR_CRASH_P4, bytes_written); /* -- 2.51.0