From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9BFCACCA476 for ; Tue, 7 Oct 2025 13:54:18 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v687Y-0000Zh-Mb; Tue, 07 Oct 2025 09:52:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v687V-0000Yc-2z for qemu-devel@nongnu.org; Tue, 07 Oct 2025 09:52:49 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v687J-00082b-EV for qemu-devel@nongnu.org; Tue, 07 Oct 2025 09:52:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1759845147; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=rMj67fa98gs98nOy1mlI50e4rz9Xdo0uNjmohFfy4co=; b=HiIgS21OW+p010s/Z0d9E88u04lXpom9b4LxxfZsszPfpDP/D2apcFqXcfdOnL6ZKDmopX ALoxzX96CxlrTci9QQFP+OkyAdElF8THhEE7AcSy8z+Xgd/poPcM9VCZkD4j/WTQSKG//g nr0W+jS5VjyOrtETWjBD7JoM2jMH3cI= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-221-A92G69fXPR-AeNHlGseObQ-1; Tue, 07 Oct 2025 09:52:23 -0400 X-MC-Unique: A92G69fXPR-AeNHlGseObQ-1 X-Mimecast-MFC-AGG-ID: A92G69fXPR-AeNHlGseObQ_1759845141 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8C5141800378; Tue, 7 Oct 2025 13:52:20 +0000 (UTC) Received: from sirius.home.kraxel.org (unknown [10.45.224.183]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 840B918004D8; Tue, 7 Oct 2025 13:52:19 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 0605D1800386; Tue, 07 Oct 2025 15:52:17 +0200 (CEST) From: Gerd Hoffmann To: qemu-devel@nongnu.org Cc: Laurent Vivier , Marcel Apfelbaum , Markus Armbruster , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Yanan Wang , Gerd Hoffmann , Paolo Bonzini , "Dr. David Alan Gilbert" , Fabiano Rosas , Eric Blake , Eduardo Habkost , Zhao Liu Subject: [PATCH v2] hw/uefi: add "info ovmf-log" + "query-ovmf-log" monitor commands Date: Tue, 7 Oct 2025 15:52:16 +0200 Message-ID: <20251007135216.1687648-1-kraxel@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kraxel@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.422, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Starting with the edk2-stable202508 tag OVMF (and ArmVirt too) have optional support for logging to a memory buffer. There is guest side support -- for example in linux kernels v6.17+ -- to read that buffer. But that might not helpful if your guest stops booting early enough that guest tooling can not be used yet. So host side support to read that log buffer is a useful thing to have. This patch implements both qmp and hmp monitor commands to read the firmware log. Signed-off-by: Gerd Hoffmann --- hw/uefi/ovmf-log.c | 237 +++++++++++++++++++++++++++++++++++++ tests/qtest/qmp-cmd-test.c | 2 + hmp-commands-info.hx | 13 ++ hw/uefi/meson.build | 2 +- qapi/machine.json | 10 ++ 5 files changed, 263 insertions(+), 1 deletion(-) create mode 100644 hw/uefi/ovmf-log.c diff --git a/hw/uefi/ovmf-log.c b/hw/uefi/ovmf-log.c new file mode 100644 index 000000000000..f7fdb1f6bcad --- /dev/null +++ b/hw/uefi/ovmf-log.c @@ -0,0 +1,237 @@ +/* + * SPDX-License-Identifier: GPL-2.0-or-later + * + * print ovmf debug log + * + * see OvmfPkg/Library/MemDebugLogLib/ in edk2 + */ + +#include "qemu/osdep.h" +#include "qemu/units.h" +#include "qemu/target-info-qapi.h" +#include "hw/boards.h" +#include "hw/i386/x86.h" +#include "hw/arm/virt.h" +#include "system/dma.h" +#include "monitor/hmp.h" +#include "monitor/monitor.h" +#include "qapi/error.h" +#include "qapi/type-helpers.h" +#include "qapi/qapi-commands-machine.h" + + +/* ----------------------------------------------------------------------- */ +/* copy from edk2 */ + +#define MEM_DEBUG_LOG_MAGIC1 0x3167646d666d766f /* "ovmfmdg1" */ +#define MEM_DEBUG_LOG_MAGIC2 0x3267646d666d766f /* "ovmfmdg2" */ + +/* + * Mem Debug Log buffer header. + * The Log buffer is circular. Only the most + * recent messages are retained. Older messages + * will be discarded if the buffer overflows. + * The Debug Log starts just after the header. + */ +typedef struct { + /* + * Magic values + * These fields are used by tools to locate the buffer in + * memory. These MUST be the first two fields of the structure. + * Use a 128 bit Magic to vastly reduce the possibility of + * a collision with random data in memory. + */ + uint64_t Magic1; + uint64_t Magic2; + /* + * Header Size + * This MUST be the third field of the structure + */ + uint64_t HeaderSize; + /* + * Debug log size (minus header) + */ + uint64_t DebugLogSize; + /* + * edk2 uses this for locking access. + */ + uint64_t MemDebugLogLock; + /* + * Debug log head offset + */ + uint64_t DebugLogHeadOffset; + /* + * Debug log tail offset + */ + uint64_t DebugLogTailOffset; + /* + * Flag to indicate if the buffer wrapped and was thus truncated. + */ + uint64_t Truncated; + /* + * Firmware Build Version (PcdFirmwareVersionString) + */ + char FirmwareVersion[128]; +} MEM_DEBUG_LOG_HDR; + + +/* ----------------------------------------------------------------------- */ +/* qemu monitor command */ + +typedef struct { + uint64_t Magic1; + uint64_t Magic2; +} MEM_DEBUG_LOG_MAGIC; + +/* find log buffer in guest memory by searching for the magic cookie */ +static dma_addr_t find_ovmf_log_range(dma_addr_t start, dma_addr_t end) +{ + static const MEM_DEBUG_LOG_MAGIC magic = { + .Magic1 = MEM_DEBUG_LOG_MAGIC1, + .Magic2 = MEM_DEBUG_LOG_MAGIC2, + }; + MEM_DEBUG_LOG_MAGIC check; + dma_addr_t step = 4 * KiB; + dma_addr_t offset; + + for (offset = start; offset < end; offset += step) { + if (dma_memory_read(&address_space_memory, offset, + &check, sizeof(check), + MEMTXATTRS_UNSPECIFIED)) { + /* dma error -> stop searching */ + break; + } + if (memcmp(&magic, &check, sizeof(check)) == 0) { + return offset; + } + } + return -1; +} + +static dma_addr_t find_ovmf_log(void) +{ + MachineState *ms = MACHINE(qdev_get_machine()); + dma_addr_t start, end, offset; + + if (target_arch() == SYS_EMU_TARGET_X86_64 && + object_dynamic_cast(OBJECT(ms), TYPE_X86_MACHINE)) { + X86MachineState *x86ms = X86_MACHINE(ms); + + /* early log buffer, static allocation in memfd, sec + early pei */ + offset = find_ovmf_log_range(0x800000, 0x900000); + if (offset != -1) { + return offset; + } + + /* + * normal log buffer, dynamically allocated close to end of low memory, + * late pei + dxe phase + */ + end = x86ms->below_4g_mem_size; + start = end - MIN(end, 128 * MiB); + offset = find_ovmf_log_range(start, end); + return offset; + } + + if (target_arch() == SYS_EMU_TARGET_AARCH64 && + object_dynamic_cast(OBJECT(ms), TYPE_VIRT_MACHINE)) { + /* edk2 ArmVirt firmware allocations are in the first 128 MB */ + VirtMachineState *vms = VIRT_MACHINE(ms); + start = vms->memmap[VIRT_MEM].base; + end = start + 128 * MiB; + offset = find_ovmf_log_range(start, end); + return offset; + } + + return -1; +} + +static void handle_ovmf_log_range(GString *out, + dma_addr_t start, + dma_addr_t end, + Error **errp) +{ + g_autofree char *buf = NULL; + + if (start > end) { + return; + } + + buf = g_malloc(end - start + 1); + if (dma_memory_read(&address_space_memory, start, + buf, end - start, + MEMTXATTRS_UNSPECIFIED)) { + error_setg(errp, "firmware log: buffer read error"); + return; + } + + buf[end - start] = 0; + g_string_append_printf(out, "%s", buf); +} + +HumanReadableText *qmp_query_ovmf_log(Error **errp) +{ + MEM_DEBUG_LOG_HDR header; + dma_addr_t offset, base; + g_autoptr(GString) out = g_string_new(""); + + offset = find_ovmf_log(); + if (offset == -1) { + error_setg(errp, "firmware log: not found"); + goto err; + } + + if (dma_memory_read(&address_space_memory, offset, + &header, sizeof(header), + MEMTXATTRS_UNSPECIFIED)) { + error_setg(errp, "firmware log: header read error"); + goto err; + } + + if (header.DebugLogSize > MiB) { + /* default size is 128k (32 pages), allow up to 1M */ + error_setg(errp, "firmware log: log buffer is too big"); + goto err; + } + + if (header.DebugLogHeadOffset > header.DebugLogSize || + header.DebugLogTailOffset > header.DebugLogSize) { + error_setg(errp, "firmware log: invalid header"); + goto err; + } + + g_string_append_printf(out, "firmware log: version \"%s\"\n", + header.FirmwareVersion); + + base = offset + header.HeaderSize; + if (header.DebugLogHeadOffset > header.DebugLogTailOffset) { + /* wrap around */ + handle_ovmf_log_range(out, + base + header.DebugLogHeadOffset, + base + header.DebugLogSize, + errp); + if (*errp) { + goto err; + } + handle_ovmf_log_range(out, + base + 0, + base + header.DebugLogTailOffset, + errp); + if (*errp) { + goto err; + } + } else { + handle_ovmf_log_range(out, + base + header.DebugLogHeadOffset, + base + header.DebugLogTailOffset, + errp); + if (*errp) { + goto err; + } + } + + return human_readable_text_from_str(out); + +err: + return NULL; +} diff --git a/tests/qtest/qmp-cmd-test.c b/tests/qtest/qmp-cmd-test.c index cf718761861d..ffdb7e979e0f 100644 --- a/tests/qtest/qmp-cmd-test.c +++ b/tests/qtest/qmp-cmd-test.c @@ -52,6 +52,8 @@ static int query_error_class(const char *cmd) /* Only valid with accel=tcg */ { "x-query-jit", ERROR_CLASS_GENERIC_ERROR }, { "xen-event-list", ERROR_CLASS_GENERIC_ERROR }, + /* requires firmware with memory buffer logging support */ + { "query-ovmf-log", ERROR_CLASS_GENERIC_ERROR }, { NULL, -1 } }; int i; diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx index 6142f60e7b16..eca0614903d1 100644 --- a/hmp-commands-info.hx +++ b/hmp-commands-info.hx @@ -977,3 +977,16 @@ SRST ``info cryptodev`` Show the crypto devices. ERST + + { + .name = "ovmf-log", + .args_type = "", + .params = "", + .help = "show the ovmf debug log", + .cmd_info_hrt = qmp_query_ovmf_log, + }, + +SRST + ``info ovmf-log`` + Show the ovmf debug log. +ERST diff --git a/hw/uefi/meson.build b/hw/uefi/meson.build index 91eb95f89e6d..c8f38dfae247 100644 --- a/hw/uefi/meson.build +++ b/hw/uefi/meson.build @@ -1,4 +1,4 @@ -system_ss.add(files('hardware-info.c')) +system_ss.add(files('hardware-info.c', 'ovmf-log.c')) uefi_vars_ss = ss.source_set() if (config_all_devices.has_key('CONFIG_UEFI_VARS')) diff --git a/qapi/machine.json b/qapi/machine.json index 038eab281c78..329034035029 100644 --- a/qapi/machine.json +++ b/qapi/machine.json @@ -1839,6 +1839,16 @@ 'returns': 'HumanReadableText', 'features': [ 'unstable' ]} +## +# @query-ovmf-log: +# +# Find firmware memory log buffer in guest memory, return content. +# +# Since: 10.2 +## +{ 'command': 'query-ovmf-log', + 'returns': 'HumanReadableText' } + ## # @dump-skeys: # -- 2.51.0