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hw/uefi/ovmf-log: add maxsize parameter

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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.

Acked-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-ID: <20251017115006.2696991-4-kraxel@redhat.com>
This commit is contained in:
Gerd Hoffmann
2025-10-17 13:50:05 +02:00
parent c8aa812031
commit c6c6d85444
3 changed files with 41 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
hmp-commands-info.hx
View File

@ -998,8 +998,8 @@ ERST
{
.name = "firmware-log",
.args_type = "",
.params = "",
.args_type = "max-size:o?",
.params = "[max-size]",
.help = "show the firmware (ovmf) debug log",
.cmd = hmp_info_firmware_log,
},

42
hw/uefi/ovmf-log.c
View File

@ -18,6 +18,7 @@
#include "qapi/error.h"
#include "qapi/type-helpers.h"
#include "qapi/qapi-commands-machine.h"
#include "qobject/qdict.h"
/* ----------------------------------------------------------------------- */
@ -164,7 +165,8 @@ static void handle_ovmf_log_range(GString *out,
}
}
FirmwareLog *qmp_query_firmware_log(Error **errp)
FirmwareLog *qmp_query_firmware_log(bool have_max_size, uint64_t max_size,
Error **errp)
{
MEM_DEBUG_LOG_HDR header;
dma_addr_t offset, base;
@ -184,18 +186,40 @@ FirmwareLog *qmp_query_firmware_log(Error **errp)
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 buffer header is invalid");
return NULL;
}
if (have_max_size) {
if (max_size > MiB) {
error_setg(errp, "parameter 'max-size' exceeds 1MiB");
return NULL;
}
} else {
max_size = MiB;
}
/* adjust header.DebugLogHeadOffset so we return at most maxsize bytes */
if (header.DebugLogHeadOffset > header.DebugLogTailOffset) {
/* wrap around */
if (header.DebugLogTailOffset > max_size) {
header.DebugLogHeadOffset = header.DebugLogTailOffset - max_size;
} else {
uint64_t max_chunk = max_size - header.DebugLogTailOffset;
if (header.DebugLogSize > max_chunk &&
header.DebugLogHeadOffset < header.DebugLogSize - max_chunk) {
header.DebugLogHeadOffset = header.DebugLogSize - max_chunk;
}
}
} else {
if (header.DebugLogTailOffset > max_size &&
header.DebugLogHeadOffset < header.DebugLogTailOffset - max_size) {
header.DebugLogHeadOffset = header.DebugLogTailOffset - max_size;
}
}
base = offset + header.HeaderSize;
if (header.DebugLogHeadOffset > header.DebugLogTailOffset) {
/* wrap around */
@ -239,8 +263,10 @@ void hmp_info_firmware_log(Monitor *mon, const QDict *qdict)
Error *err = NULL;
FirmwareLog *log;
gsize log_len;
int64_t maxsize;
log = qmp_query_firmware_log(&err);
maxsize = qdict_get_try_int(qdict, "max-size", -1);
log = qmp_query_firmware_log(maxsize != -1, (uint64_t)maxsize, &err);
if (err) {
hmp_handle_error(mon, err);
return;

5
qapi/machine.json
View File

@ -1858,9 +1858,14 @@
#
# Find firmware memory log buffer in guest memory, return content.
#
# @max-size: limit the amount of log data returned. Up to 1 MiB of
# log data is allowed. In case the amount of log data is
# larger than @max-size the tail of the log is returned.
#
# Since: 10.2
##
{ 'command': 'query-firmware-log',
'data': { '*max-size': 'size' },
'returns': 'FirmwareLog' }
##