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Tsirkin" , "Igor Mammedov" , "Ani Sinha" , "Eduardo Habkost" , "Marcel Apfelbaum" , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , "Yanan Wang" , "Zhao Liu" , "Song Gao" , "Jiaxun Yang" , "Sunil V L" , "Palmer Dabbelt" , "Alistair Francis" , "Weiwei Li" , "qemu-arm" , "qemu-devel" , "qemu-riscv" Cc: Li Chen , Bibo Mao , Gavin Shan Subject: [PATCH REPOST v4 1/4] acpi: Add machine option to disable SPCR table Date: Wed, 28 May 2025 18:53:35 +0800 Message-ID: <20250528105404.457729-2-me@linux.beauty> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250528105404.457729-1-me@linux.beauty> References: <20250528105404.457729-1-me@linux.beauty> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMailClient: External Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=136.143.188.15; envelope-from=me@linux.beauty; helo=sender4-op-o15.zoho.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, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity me@linux.beauty) X-ZM-MESSAGEID: 1748429914072116600 From: Li Chen The ACPI SPCR (Serial Port Console Redirection) table allows firmware to specify a preferred serial console device to the operating system. On ARM64 systems, Linux by default respects this table: even if the kernel command line does not include a hardware serial console (e.g., "console=3DttyAMA0"), the kernel still register the serial device referenced by SPCR as a printk console. While this behavior is standard-compliant, it can lead to situations where guest console behavior is influenced by platform firmware rather than user-specified configuration. To make guest console behavior more predictable and under user control, this patch introduces a machine option to explicitly disable SPCR table exposure: -machine spcr=3Doff By default, the option is enabled (spcr=3Don), preserving existing behavior. When disabled, QEMU will omit the SPCR table from the guest's ACPI namespace, ensuring that only consoles explicitly declared in the kernel command line are registered. Signed-off-by: Li Chen Reviewed-by: Bibo Mao Acked-by: Michael S. Tsirkin Reviewed-by: Gavin Shan Reviewed-by: Sunil V L --- Notes: Changes since v3: 1. Add Reviewed-by from Sunil V L 2. rename enable_spcr to acpi_spcr_enabled as suggested by Philippe Mathieu-Daud=C3=A9 Changes since V2: Add Reviewed-by from Gavin Shan for the first patch and fix style issue. Changes since V1: add Reviewed-by and Acked-by hw/arm/virt-acpi-build.c | 5 ++++- hw/core/machine.c | 22 ++++++++++++++++++++++ hw/loongarch/virt-acpi-build.c | 4 +++- hw/riscv/virt-acpi-build.c | 5 ++++- include/hw/boards.h | 1 + qemu-options.hx | 5 +++++ 6 files changed, 39 insertions(+), 3 deletions(-) diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c index 7e8e0f0298..d77d16cbd3 100644 --- a/hw/arm/virt-acpi-build.c +++ b/hw/arm/virt-acpi-build.c @@ -936,7 +936,10 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildT= ables *tables) } =20 acpi_add_table(table_offsets, tables_blob); - spcr_setup(tables_blob, tables->linker, vms); + + if (ms->acpi_spcr_enabled) { + spcr_setup(tables_blob, tables->linker, vms); + } =20 acpi_add_table(table_offsets, tables_blob); build_dbg2(tables_blob, tables->linker, vms); diff --git a/hw/core/machine.c b/hw/core/machine.c index c3f3a5020d..4438eeff54 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -595,6 +595,20 @@ static void machine_set_nvdimm(Object *obj, bool value= , Error **errp) ms->nvdimms_state->is_enabled =3D value; } =20 +static bool machine_get_spcr(Object *obj, Error **errp) +{ + MachineState *ms =3D MACHINE(obj); + + return ms->acpi_spcr_enabled; +} + +static void machine_set_spcr(Object *obj, bool value, Error **errp) +{ + MachineState *ms =3D MACHINE(obj); + + ms->acpi_spcr_enabled =3D value; +} + static bool machine_get_hmat(Object *obj, Error **errp) { MachineState *ms =3D MACHINE(obj); @@ -1299,6 +1313,14 @@ static void machine_initfn(Object *obj) "Table (HMAT)"); } =20 + /* SPCR */ + ms->acpi_spcr_enabled =3D true; + object_property_add_bool(obj, "spcr", machine_get_spcr, machine_set_sp= cr); + object_property_set_description(obj, "spcr", + "Set on/off to enable/disable " + "ACPI Serial Port Console Redirection " + "Table (spcr)"); + /* default to mc->default_cpus */ ms->smp.cpus =3D mc->default_cpus; ms->smp.max_cpus =3D mc->default_cpus; diff --git a/hw/loongarch/virt-acpi-build.c b/hw/loongarch/virt-acpi-build.c index 073b6de75c..15a56280a0 100644 --- a/hw/loongarch/virt-acpi-build.c +++ b/hw/loongarch/virt-acpi-build.c @@ -557,7 +557,9 @@ static void acpi_build(AcpiBuildTables *tables, Machine= State *machine) acpi_add_table(table_offsets, tables_blob); build_srat(tables_blob, tables->linker, machine); acpi_add_table(table_offsets, tables_blob); - spcr_setup(tables_blob, tables->linker, machine); + + if (machine->acpi_spcr_enabled) + spcr_setup(tables_blob, tables->linker, machine); =20 if (machine->numa_state->num_nodes) { if (machine->numa_state->have_numa_distance) { diff --git a/hw/riscv/virt-acpi-build.c b/hw/riscv/virt-acpi-build.c index 8b5683dbde..ee1416d264 100644 --- a/hw/riscv/virt-acpi-build.c +++ b/hw/riscv/virt-acpi-build.c @@ -894,7 +894,10 @@ static void virt_acpi_build(RISCVVirtState *s, AcpiBui= ldTables *tables) } =20 acpi_add_table(table_offsets, tables_blob); - spcr_setup(tables_blob, tables->linker, s); + + if (ms->acpi_spcr_enabled) { + spcr_setup(tables_blob, tables->linker, s); + } =20 acpi_add_table(table_offsets, tables_blob); { diff --git a/include/hw/boards.h b/include/hw/boards.h index a7b1fcffae..e29fadd300 100644 --- a/include/hw/boards.h +++ b/include/hw/boards.h @@ -444,6 +444,7 @@ struct MachineState { SmpCache smp_cache; struct NVDIMMState *nvdimms_state; struct NumaState *numa_state; + bool acpi_spcr_enabled; }; =20 /* diff --git a/qemu-options.hx b/qemu-options.hx index 7eb8e02b4b..eac8730692 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -38,6 +38,7 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \ " nvdimm=3Don|off controls NVDIMM support (default=3Dof= f)\n" " memory-encryption=3D@var{} memory encryption object t= o use (default=3Dnone)\n" " hmat=3Don|off controls ACPI HMAT support (default=3Do= ff)\n" + " spcr=3Don|off controls ACPI SPCR support (default=3Do= n)\n" #ifdef CONFIG_POSIX " aux-ram-share=3Don|off allocate auxiliary guest RAM a= s shared (default: off)\n" #endif @@ -105,6 +106,10 @@ SRST Enables or disables ACPI Heterogeneous Memory Attribute Table (HMAT) support. The default is off. =20 + ``spcr=3Don|off`` + Enables or disables ACPI Serial Port Console Redirection Table + (SPCR) support. The default is on. + ``aux-ram-share=3Don|off`` Allocate auxiliary guest RAM as an anonymous file that is shareable with an external process. This option applies to --=20 2.49.0