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 73B32CCD184 for ; Tue, 14 Oct 2025 12:05:35 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v8dkz-0003VF-AE; Tue, 14 Oct 2025 08:03:57 -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 1v8dkw-0003Uu-5M for qemu-devel@nongnu.org; Tue, 14 Oct 2025 08:03:54 -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 1v8dkm-0006n3-TR for qemu-devel@nongnu.org; Tue, 14 Oct 2025 08:03:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760443417; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=DWdRGgbkBIL0htD3F9qyfxA9+XQQneG6Ik05TIvD670=; b=Zgk0P3lJ+raTbN7jS2GkG2nnYP5tE3kVHe3JmdE3aDDNJ+jMtxOO2W3M/E8k/t1ECkIp5R wNfFDm9zj0tMAVGr8lklEt5PlqQrRHR1DRJz8KwnaMk0lKBvjXm4EU2hbPend9aKfzVD3I 1GmWXEvC/eJiiCCP4CRwFMGCcC92dn4= Received: from mx-prod-mc-08.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-599-hOca7Mc0PtW5S4w7RtxzYQ-1; Tue, 14 Oct 2025 08:03:34 -0400 X-MC-Unique: hOca7Mc0PtW5S4w7RtxzYQ-1 X-Mimecast-MFC-AGG-ID: hOca7Mc0PtW5S4w7RtxzYQ_1760443413 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5C4171800452; Tue, 14 Oct 2025 12:03:32 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.19]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 21B0130002D0; Tue, 14 Oct 2025 12:03:31 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 926A721E6A27; Tue, 14 Oct 2025 14:03:28 +0200 (CEST) From: Markus Armbruster To: Gerd Hoffmann Cc: qemu-devel@nongnu.org, Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Marcel Apfelbaum , Yanan Wang , Paolo Bonzini , Fabiano Rosas , Eric Blake , Eduardo Habkost , "Dr. David Alan Gilbert" , Laurent Vivier , Zhao Liu Subject: Re: [PATCH v4 1/2] hw/uefi: add "info firmware-log" + "query-firmware-log" monitor commands In-Reply-To: <20251013104954.250166-2-kraxel@redhat.com> (Gerd Hoffmann's message of "Mon, 13 Oct 2025 12:49:53 +0200") References: <20251013104954.250166-1-kraxel@redhat.com> <20251013104954.250166-2-kraxel@redhat.com> Date: Tue, 14 Oct 2025 14:03:28 +0200 Message-ID: <87qzv5oflb.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_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 Gerd Hoffmann writes: > 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 > --- > include/monitor/hmp.h | 1 + > hw/uefi/ovmf-log.c | 267 +++++++++++++++++++++++++++++++++++++ > tests/qtest/qmp-cmd-test.c | 2 + > hmp-commands-info.hx | 14 ++ > hw/uefi/meson.build | 2 +- > qapi/machine.json | 23 ++++ > 6 files changed, 308 insertions(+), 1 deletion(-) > create mode 100644 hw/uefi/ovmf-log.c > > diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h > index ae116d9804a3..885c0ecd2aed 100644 > --- a/include/monitor/hmp.h > +++ b/include/monitor/hmp.h > @@ -178,5 +178,6 @@ void hmp_boot_set(Monitor *mon, const QDict *qdict); > void hmp_info_mtree(Monitor *mon, const QDict *qdict); > void hmp_info_cryptodev(Monitor *mon, const QDict *qdict); > void hmp_dumpdtb(Monitor *mon, const QDict *qdict); > +void hmp_info_firmware_log(Monitor *mon, const QDict *qdict); > > #endif > diff --git a/hw/uefi/ovmf-log.c b/hw/uefi/ovmf-log.c > new file mode 100644 > index 000000000000..f03e47a290d6 > --- /dev/null > +++ b/hw/uefi/ovmf-log.c > @@ -0,0 +1,267 @@ > +/* > + * 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/base64.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; You changed capitalization. Intentional? > + > +/* 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 (dma_addr_t)-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); > + return find_ovmf_log_range(start, end); > + } > + > + if (target_arch() == SYS_EMU_TARGET_AARCH64 && > + object_dynamic_cast(OBJECT(ms), TYPE_VIRT_MACHINE)) { > + VirtMachineState *vms = VIRT_MACHINE(ms); > + > + /* edk2 ArmVirt firmware allocations are in the first 128 MB */ > + start = vms->memmap[VIRT_MEM].base; > + end = start + 128 * MiB; > + return find_ovmf_log_range(start, end); > + } > + > + return (dma_addr_t)-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; > + } > + > + size_t len = end - start; > + g_string_set_size(out, out->len + len); > + if (dma_memory_read(&address_space_memory, start, > + out->str + (out->len - len), > + len, MEMTXATTRS_UNSPECIFIED)) { > + error_setg(errp, "firmware log: buffer read error"); > + return; > + } > +} > + > +FirmwareLog *qmp_query_firmware_log(Error **errp) > +{ > + MEM_DEBUG_LOG_HDR header; > + dma_addr_t offset, base; > + FirmwareLog *ret; > + g_autoptr(GString) log = g_string_new(""); > + > + offset = find_ovmf_log(); > + if (offset == -1) { > + error_setg(errp, "firmware log: not found"); > + return NULL; > + } > + > + if (dma_memory_read(&address_space_memory, offset, > + &header, sizeof(header), > + MEMTXATTRS_UNSPECIFIED)) { > + error_setg(errp, "firmware log: header read error"); > + return NULL; > + } > + > + if (header.DebugLogSize > MiB) { > + /* default size is 128k (32 pages), allow up to 1M */ > + error_setg(errp, "firmware log: log buffer is too big"); > + return NULL; > + } > + > + if (header.DebugLogHeadOffset > header.DebugLogSize || > + header.DebugLogTailOffset > header.DebugLogSize) { > + error_setg(errp, "firmware log: invalid header"); > + return NULL; > + } > + > + base = offset + header.HeaderSize; > + if (header.DebugLogHeadOffset > header.DebugLogTailOffset) { > + /* wrap around */ > + handle_ovmf_log_range(log, > + base + header.DebugLogHeadOffset, > + base + header.DebugLogSize, > + errp); > + if (*errp) { > + return NULL; > + } > + handle_ovmf_log_range(log, > + base + 0, > + base + header.DebugLogTailOffset, > + errp); > + if (*errp) { > + return NULL; > + } > + } else { > + handle_ovmf_log_range(log, > + base + header.DebugLogHeadOffset, > + base + header.DebugLogTailOffset, > + errp); > + if (*errp) { > + return NULL; > + } > + } > + > + ret = g_new0(FirmwareLog, 1); > + ret->version = g_strndup(header.FirmwareVersion, > + sizeof(header.FirmwareVersion)); > + ret->log = g_base64_encode((const guchar *)log->str, log->len); > + return ret; > +} > + > +void hmp_info_firmware_log(Monitor *mon, const QDict *qdict) > +{ > + Error *errp = NULL; Unusual identifier. By convention, we use @errp for Error **, and @err for Error *. Missed this in v3, sorry. > + FirmwareLog *log; > + > + log = qmp_query_firmware_log(&errp); > + if (errp) { > + hmp_handle_error(mon, errp); > + return; > + } > + > + g_assert(log != NULL); > + > + if (log->version) { > + g_autofree gchar *esc = g_strescape(log->version, NULL); > + monitor_printf(mon, "[ firmware version: %s ]\n", esc); > + } > + > + if (log->log) { > + g_autofree gchar *esc = NULL; > + g_autofree gchar *out = NULL; > + size_t outlen; > + > + out = (gchar *)qbase64_decode(log->log, -1, &outlen, &errp); > + if (errp) { How can this happen? > + hmp_handle_error(mon, errp); > + return; > + } > + esc = g_strescape(out, "\r\n"); > + monitor_printf(mon, "%s\n", esc); > + } > +} > 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..257015f0b403 100644 > --- a/hmp-commands-info.hx > +++ b/hmp-commands-info.hx > @@ -977,3 +977,17 @@ SRST > ``info cryptodev`` > Show the crypto devices. > ERST > + > + { > + .name = "firmware-log", > + .args_type = "", > + .params = "", > + .help = "show the firmware (ovmf) debug log", > + .cmd = hmp_info_firmware_log, > + .flags = "p", > + }, > + > +SRST > + ``info firmware-log`` > + Show the firmware (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..c96e582afdd6 100644 > --- a/qapi/machine.json > +++ b/qapi/machine.json > @@ -1839,6 +1839,29 @@ > 'returns': 'HumanReadableText', > 'features': [ 'unstable' ]} > > +## > +# @FirmwareLog: > +# > +# @version: Firmware version. > +# > +# @log: Firmware debug log, in base64 encoding. Recomment to document that @log can start and end with a partial line. > +# > +# Since: 10.2 > +## > +{ 'struct': 'FirmwareLog', > + 'data': { '*version': 'str', > + '*log': 'str' } } > + > +## > +# @query-firmware-log: > +# > +# Find firmware memory log buffer in guest memory, return content. > +# > +# Since: 10.2 > +## > +{ 'command': 'query-firmware-log', > + 'returns': 'FirmwareLog' } > + > ## > # @dump-skeys: > #