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 1AADECCD187 for ; Tue, 14 Oct 2025 08:57:29 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v8aq5-000691-Vo; Tue, 14 Oct 2025 04:57:02 -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 1v8aq4-00068s-T7 for qemu-devel@nongnu.org; Tue, 14 Oct 2025 04:57:00 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v8aq1-0007Xk-90 for qemu-devel@nongnu.org; Tue, 14 Oct 2025 04:57:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760432215; h=from:from:reply-to: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=JG0nljE1uvF8rOVPOA6b6wqCFLyeXeIK9yh62Gc/ou4=; b=fP3iFi27swpOGXbKJTUy8uZjWlkK3shWZOq7a5OqqajC+Kf0sa0EOrcWzPz5ILR3I+GfzM W8EDLZhRgIH+Td8Zs7JCVEGhnjpJl8A994NERJ2HsOob0NfsAIOF+3Ds3ZjrpKDm0JkvlU kSmW+/yNM6bafDjjJQ4DpCIdj+eCCds= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-210-wNCNyDIePOOp3RQHFGecnA-1; Tue, 14 Oct 2025 04:56:51 -0400 X-MC-Unique: wNCNyDIePOOp3RQHFGecnA-1 X-Mimecast-MFC-AGG-ID: wNCNyDIePOOp3RQHFGecnA_1760432210 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7E90F1955F0D; Tue, 14 Oct 2025 08:56:49 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.198]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id BA9421800446; Tue, 14 Oct 2025 08:56:44 +0000 (UTC) Date: Tue, 14 Oct 2025 09:56:40 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Gerd Hoffmann Cc: qemu-devel@nongnu.org, Philippe =?utf-8?Q?Mathieu-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 Subject: Re: [PATCH v4 1/2] hw/uefi: add "info firmware-log" + "query-firmware-log" monitor commands Message-ID: References: <20251013104954.250166-1-kraxel@redhat.com> <20251013104954.250166-2-kraxel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251013104954.250166-2-kraxel@redhat.com> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Oct 13, 2025 at 12:49:53PM +0200, Gerd Hoffmann wrote: > 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; > + > +/* 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; Left-over variable - unfortunately gcc doens't warn about unused vars when g_autofree is present :-( > + > + 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; > + } > +} > 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. > +# > +# Since: 10.2 > +## > +{ 'struct': 'FirmwareLog', > + 'data': { '*version': 'str', > + '*log': 'str' } } Having version be optional makes sense, but what is the semantics for 'log' being optional. If the log is unavailable, wouldn't we be better raising an error ? With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|