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Mon, 13 Oct 2025 12:49:54 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760352605; 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: in-reply-to:in-reply-to:references:references; bh=pSsOu1yanCiquZgewgylmKB+MTREEWQxuevtsVxqotU=; b=jI55MeWnCKX1nyrXmVwATEce4931/AHpeYtSDSQgYUTGE0QSm5Ku4kgyBZHL7uC9RYrP0i D2bvInhYSCGpr6afBUultYonO2YzaJR9+I3mx3Llns9QM0v2EZC41nys8Vm6rpfcnBnzv3 QKaQYQq5RdxzEGTOKsTxI/zE+NkGL74= X-MC-Unique: c_FB4rfcMKe7y_paCQ2-YQ-1 X-Mimecast-MFC-AGG-ID: c_FB4rfcMKe7y_paCQ2-YQ_1760352598 From: Gerd Hoffmann To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Marcel Apfelbaum , Yanan Wang , Markus Armbruster , Paolo Bonzini , Fabiano Rosas , Eric Blake , Eduardo Habkost , "Dr. David Alan Gilbert" , Laurent Vivier , Zhao Liu , Gerd Hoffmann Subject: [PATCH v4 1/2] hw/uefi: add "info firmware-log" + "query-firmware-log" monitor commands Date: Mon, 13 Oct 2025 12:49:53 +0200 Message-ID: <20251013104954.250166-2-kraxel@redhat.com> In-Reply-To: <20251013104954.250166-1-kraxel@redhat.com> References: <20251013104954.250166-1-kraxel@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" 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); =20 #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; + +/* 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 =3D { + .magic1 =3D MEM_DEBUG_LOG_MAGIC1, + .magic2 =3D MEM_DEBUG_LOG_MAGIC2, + }; + MEM_DEBUG_LOG_MAGIC check; + dma_addr_t step =3D 4 * KiB; + dma_addr_t offset; + + for (offset =3D start; offset < end; offset +=3D 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)) =3D=3D 0) { + return offset; + } + } + return (dma_addr_t)-1; +} + +static dma_addr_t find_ovmf_log(void) +{ + MachineState *ms =3D MACHINE(qdev_get_machine()); + dma_addr_t start, end, offset; + + if (target_arch() =3D=3D SYS_EMU_TARGET_X86_64 && + object_dynamic_cast(OBJECT(ms), TYPE_X86_MACHINE)) { + X86MachineState *x86ms =3D X86_MACHINE(ms); + + /* early log buffer, static allocation in memfd, sec + early pei */ + offset =3D find_ovmf_log_range(0x800000, 0x900000); + if (offset !=3D -1) { + return offset; + } + + /* + * normal log buffer, dynamically allocated close to end of low me= mory, + * late pei + dxe phase + */ + end =3D x86ms->below_4g_mem_size; + start =3D end - MIN(end, 128 * MiB); + return find_ovmf_log_range(start, end); + } + + if (target_arch() =3D=3D SYS_EMU_TARGET_AARCH64 && + object_dynamic_cast(OBJECT(ms), TYPE_VIRT_MACHINE)) { + VirtMachineState *vms =3D VIRT_MACHINE(ms); + + /* edk2 ArmVirt firmware allocations are in the first 128 MB */ + start =3D vms->memmap[VIRT_MEM].base; + end =3D 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 =3D NULL; + + if (start > end) { + return; + } + + size_t len =3D 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 =3D g_string_new(""); + + offset =3D find_ovmf_log(); + if (offset =3D=3D -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 =3D 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 =3D g_new0(FirmwareLog, 1); + ret->version =3D g_strndup(header.FirmwareVersion, + sizeof(header.FirmwareVersion)); + ret->log =3D g_base64_encode((const guchar *)log->str, log->len); + return ret; +} + +void hmp_info_firmware_log(Monitor *mon, const QDict *qdict) +{ + Error *errp =3D NULL; + FirmwareLog *log; + + log =3D qmp_query_firmware_log(&errp); + if (errp) { + hmp_handle_error(mon, errp); + return; + } + + g_assert(log !=3D NULL); + + if (log->version) { + g_autofree gchar *esc =3D g_strescape(log->version, NULL); + monitor_printf(mon, "[ firmware version: %s ]\n", esc); + } + + if (log->log) { + g_autofree gchar *esc =3D NULL; + g_autofree gchar *out =3D NULL; + size_t outlen; + + out =3D (gchar *)qbase64_decode(log->log, -1, &outlen, &errp); + if (errp) { + hmp_handle_error(mon, errp); + return; + } + esc =3D 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=3Dtcg */ { "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 =3D "firmware-log", + .args_type =3D "", + .params =3D "", + .help =3D "show the firmware (ovmf) debug log", + .cmd =3D hmp_info_firmware_log, + .flags =3D "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')) =20 uefi_vars_ss =3D 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' ]} =20 +## +# @FirmwareLog: +# +# @version: Firmware version. +# +# @log: Firmware debug log, in base64 encoding. +# +# 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: # --=20 2.51.0 From nobody Fri Nov 14 18:21:16 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; 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Mon, 13 Oct 2025 12:49:54 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760352607; 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: in-reply-to:in-reply-to:references:references; bh=OvZxEGssQt5lRMdeoL8b/rdzkt3zolTRm5uuvD75DF8=; b=CmsFCQ+byIufETy8C0wnGnhkMdV4pJxmoQhBl47XGOMuOqq2fO+cps7ZHG4aFmt/T7oTb0 fDuJEzGvsdUzmvKoLnnbiUhub+edRDxdmHB1H2tiyxQ33GHnwzfraNjGDUUuJcG9sFuFgS 1yOuv+1xGHP+WClPi/9+MobPu4S1CdI= X-MC-Unique: eZk9mgGYOcW8h914sJyl8A-1 X-Mimecast-MFC-AGG-ID: eZk9mgGYOcW8h914sJyl8A_1760352601 From: Gerd Hoffmann To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Marcel Apfelbaum , Yanan Wang , Markus Armbruster , Paolo Bonzini , Fabiano Rosas , Eric Blake , Eduardo Habkost , "Dr. David Alan Gilbert" , Laurent Vivier , Zhao Liu , Gerd Hoffmann Subject: [PATCH v4 2/2] hw/uefi/ovmf-log: add maxsize parameter Date: Mon, 13 Oct 2025 12:49:54 +0200 Message-ID: <20251013104954.250166-3-kraxel@redhat.com> In-Reply-To: <20251013104954.250166-1-kraxel@redhat.com> References: <20251013104954.250166-1-kraxel@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" Allow limiting the amount of log output sent. Allow up to 1 MiB. In case the guest log buffer is larger than 1 MiB limit the output instead of throwing an error. Signed-off-by: Gerd Hoffmann Reviewed-by: Daniel P. Berrang=C3=A9 --- hw/uefi/ovmf-log.c | 40 ++++++++++++++++++++++++++++++++-------- hmp-commands-info.hx | 5 ++--- qapi/machine.json | 3 +++ 3 files changed, 37 insertions(+), 11 deletions(-) diff --git a/hw/uefi/ovmf-log.c b/hw/uefi/ovmf-log.c index f03e47a290d6..9d9dc7b0d8d5 100644 --- a/hw/uefi/ovmf-log.c +++ b/hw/uefi/ovmf-log.c @@ -19,6 +19,7 @@ #include "qapi/error.h" #include "qapi/type-helpers.h" #include "qapi/qapi-commands-machine.h" +#include "qobject/qdict.h" =20 =20 /* -----------------------------------------------------------------------= */ @@ -167,7 +168,8 @@ static void handle_ovmf_log_range(GString *out, } } =20 -FirmwareLog *qmp_query_firmware_log(Error **errp) +FirmwareLog *qmp_query_firmware_log(bool have_maxsize, uint64_t maxsize, + Error **errp) { MEM_DEBUG_LOG_HDR header; dma_addr_t offset, base; @@ -187,18 +189,38 @@ FirmwareLog *qmp_query_firmware_log(Error **errp) return NULL; } =20 - 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; } =20 + if (!have_maxsize) { + maxsize =3D MiB; + } + if (maxsize > MiB) { + maxsize =3D MiB; + } + + /* adjust header.DebugLogHeadOffset so we rezturn at most maxsize byte= s */ + if (header.DebugLogHeadOffset > header.DebugLogTailOffset) { + /* wrap around */ + if (header.DebugLogTailOffset > maxsize) { + header.DebugLogHeadOffset =3D header.DebugLogTailOffset - maxs= ize; + } else { + uint64_t maxchunk =3D maxsize - header.DebugLogTailOffset; + if (header.DebugLogSize > maxchunk && + header.DebugLogHeadOffset < header.DebugLogSize - maxchunk= ) { + header.DebugLogHeadOffset =3D header.DebugLogSize - maxchu= nk; + } + } + } else { + if (header.DebugLogTailOffset > maxsize && + header.DebugLogHeadOffset < header.DebugLogTailOffset - maxsiz= e) { + header.DebugLogHeadOffset =3D header.DebugLogTailOffset - maxs= ize; + } + } + base =3D offset + header.HeaderSize; if (header.DebugLogHeadOffset > header.DebugLogTailOffset) { /* wrap around */ @@ -237,8 +259,10 @@ void hmp_info_firmware_log(Monitor *mon, const QDict *= qdict) { Error *errp =3D NULL; FirmwareLog *log; + int64_t maxsize; =20 - log =3D qmp_query_firmware_log(&errp); + maxsize =3D qdict_get_try_int(qdict, "maxsize", -1); + log =3D qmp_query_firmware_log(maxsize !=3D -1, (uint64_t)maxsize, &er= rp); if (errp) { hmp_handle_error(mon, errp); return; diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx index 257015f0b403..db03d88d3c74 100644 --- a/hmp-commands-info.hx +++ b/hmp-commands-info.hx @@ -980,11 +980,10 @@ ERST =20 { .name =3D "firmware-log", - .args_type =3D "", - .params =3D "", + .args_type =3D "maxsize:i?", + .params =3D "[maxsize]", .help =3D "show the firmware (ovmf) debug log", .cmd =3D hmp_info_firmware_log, - .flags =3D "p", }, =20 SRST diff --git a/qapi/machine.json b/qapi/machine.json index c96e582afdd6..d0c6d3ede027 100644 --- a/qapi/machine.json +++ b/qapi/machine.json @@ -1857,9 +1857,12 @@ # # Find firmware memory log buffer in guest memory, return content. # +# @maxsize: limit the amount of logdata returned. +# # Since: 10.2 ## { 'command': 'query-firmware-log', + 'data': { '*maxsize': 'size' }, 'returns': 'FirmwareLog' } =20 ## --=20 2.51.0