From: Li Chen <[email protected]> virt machines always instantiate a PL011/16550 UART at slot 0 and describe it in ACPI (DSDT and optional SPCR table). When the command line disables the serial backend (e.g. "-serial none"), the guest still sees the UART as a preferred console even though it is not usable.
Teach the virt ACPI code to omit the UART device and SPCR when there is no serial backend attached. This matches the hardware that the guest can actually use and avoids confusing firmware or OS code that relies on SPCR. The bios-tables-test qtests rely on an ACPI UART node and SPCR entry for UEFI-based virt machines. To keep those tests working we create a UART with a "null" chardev backend instead. This preserves the ACPI tables while discarding the firmware's serial output so it does not corrupt the TAP stdout stream. Suggested-by: Philippe Mathieu-Daudé <[email protected]> Signed-off-by: Li Chen <[email protected]> Reviewed-by: Sunil V L <[email protected]> --- v4->v5: - Also suppress UART device & SPCR when guest has no serial hardware on loongarch - rename serial_exist to serial_exists - fix style issue v5->v6: - Fix: tap parsingg error caused by changing serial to none; now set to null. hw/arm/virt-acpi-build.c | 15 +++++++++------ hw/loongarch/virt-acpi-build.c | 8 +++++--- hw/riscv/virt-acpi-build.c | 8 ++++++-- include/system/system.h | 2 ++ system/vl.c | 5 +++++ tests/qtest/bios-tables-test.c | 6 ++++-- 6 files changed, 31 insertions(+), 13 deletions(-) diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c index 200e2a1da7..16d3b63030 100644 --- a/hw/arm/virt-acpi-build.c +++ b/hw/arm/virt-acpi-build.c @@ -64,6 +64,7 @@ #include "hw/virtio/virtio-acpi.h" #include "target/arm/cpu.h" #include "target/arm/multiprocessing.h" +#include "system/system.h" #define ARM_SPI_BASE 32 @@ -1031,11 +1032,13 @@ build_dsdt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms) */ scope = aml_scope("\\_SB"); acpi_dsdt_add_cpus(scope, vms); - acpi_dsdt_add_uart(scope, &memmap[VIRT_UART0], - (irqmap[VIRT_UART0] + ARM_SPI_BASE), 0); - if (vms->second_ns_uart_present) { - acpi_dsdt_add_uart(scope, &memmap[VIRT_UART1], - (irqmap[VIRT_UART1] + ARM_SPI_BASE), 1); + if (serial_exists()) { + acpi_dsdt_add_uart(scope, &memmap[VIRT_UART0], + (irqmap[VIRT_UART0] + ARM_SPI_BASE), 0); + if (vms->second_ns_uart_present) { + acpi_dsdt_add_uart(scope, &memmap[VIRT_UART1], + (irqmap[VIRT_UART1] + ARM_SPI_BASE), 1); + } } if (vmc->acpi_expose_flash) { acpi_dsdt_add_flash(scope, &memmap[VIRT_FLASH]); @@ -1184,7 +1187,7 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables) acpi_add_table(table_offsets, tables_blob); - if (ms->acpi_spcr_enabled) { + if (ms->acpi_spcr_enabled && serial_exists()) { spcr_setup(tables_blob, tables->linker, vms); } diff --git a/hw/loongarch/virt-acpi-build.c b/hw/loongarch/virt-acpi-build.c index 3694c9827f..6eab907087 100644 --- a/hw/loongarch/virt-acpi-build.c +++ b/hw/loongarch/virt-acpi-build.c @@ -484,8 +484,10 @@ build_dsdt(GArray *table_data, BIOSLinker *linker, MachineState *machine) acpi_table_begin(&table, table_data); dsdt = init_aml_allocator(); - for (i = 0; i < VIRT_UART_COUNT; i++) { - build_uart_device_aml(dsdt, i); + if (serial_exists()) { + for (i = 0; i < VIRT_UART_COUNT; i++) { + build_uart_device_aml(dsdt, i); + } } build_pci_device_aml(dsdt, lvms); build_la_ged_aml(dsdt, machine); @@ -557,7 +559,7 @@ static void acpi_build(AcpiBuildTables *tables, MachineState *machine) build_srat(tables_blob, tables->linker, machine); acpi_add_table(table_offsets, tables_blob); - if (machine->acpi_spcr_enabled) + if (machine->acpi_spcr_enabled && serial_exists()) spcr_setup(tables_blob, tables->linker, machine); if (machine->numa_state->num_nodes) { diff --git a/hw/riscv/virt-acpi-build.c b/hw/riscv/virt-acpi-build.c index f1406cb683..e895bc4ddb 100644 --- a/hw/riscv/virt-acpi-build.c +++ b/hw/riscv/virt-acpi-build.c @@ -39,6 +39,7 @@ #include "qapi/error.h" #include "qemu/error-report.h" #include "system/reset.h" +#include "system/system.h" #define ACPI_BUILD_TABLE_SIZE 0x20000 #define ACPI_BUILD_INTC_ID(socket, index) ((socket << 24) | (index)) @@ -474,7 +475,10 @@ static void build_dsdt(GArray *table_data, memmap[VIRT_APLIC_S].size, "RSCV0002"); } - acpi_dsdt_add_uart(scope, &memmap[VIRT_UART0], UART0_IRQ); + if (serial_exists()) { + acpi_dsdt_add_uart(scope, &memmap[VIRT_UART0], UART0_IRQ); + } + if (virt_is_iommu_sys_enabled(s)) { acpi_dsdt_add_iommu_sys(scope, &memmap[VIRT_IOMMU_SYS], IOMMU_SYS_IRQ); } @@ -890,7 +894,7 @@ static void virt_acpi_build(RISCVVirtState *s, AcpiBuildTables *tables) acpi_add_table(table_offsets, tables_blob); - if (ms->acpi_spcr_enabled) { + if (ms->acpi_spcr_enabled && serial_exists()) { spcr_setup(tables_blob, tables->linker, s); } diff --git a/include/system/system.h b/include/system/system.h index 03a2d0e900..4a03f17e91 100644 --- a/include/system/system.h +++ b/include/system/system.h @@ -74,6 +74,8 @@ extern unsigned int nb_prom_envs; /* Return the Chardev for serial port i, or NULL if none */ Chardev *serial_hd(int i); +bool serial_exists(void); + /* parallel ports */ #define MAX_PARALLEL_PORTS 3 diff --git a/system/vl.c b/system/vl.c index 5091fe52d9..3a2988cb47 100644 --- a/system/vl.c +++ b/system/vl.c @@ -1487,6 +1487,11 @@ Chardev *serial_hd(int i) return NULL; } +bool serial_exists(void) +{ + return serial_hd(0) ? true : false; +} + static bool parallel_parse(const char *devname, Error **errp) { static int index = 0; diff --git a/tests/qtest/bios-tables-test.c b/tests/qtest/bios-tables-test.c index 6b892ef23e..6b0e4be752 100644 --- a/tests/qtest/bios-tables-test.c +++ b/tests/qtest/bios-tables-test.c @@ -824,10 +824,12 @@ static char *test_acpi_create_args(test_data *data, const char *params) /* * TODO: convert '-drive if=pflash' to new syntax (see e33763be7cd3) * when arm/virt boad starts to support it. + * NOTE: Explicitly add "-serial null" to enable uart in DSDT + * without mixing guest output into TAP stdout. */ if (data->cd) { args = g_strdup_printf("-machine %s%s %s -accel tcg " - "-nodefaults -nographic " + "-nodefaults -serial null -nographic " "-drive if=pflash,format=raw,file=%s,readonly=on " "-drive if=pflash,format=raw,file=%s,snapshot=on -cdrom %s %s", data->machine, data->machine_param ?: "", @@ -835,7 +837,7 @@ static char *test_acpi_create_args(test_data *data, const char *params) data->uefi_fl1, data->uefi_fl2, data->cd, params ? params : ""); } else { args = g_strdup_printf("-machine %s%s %s -accel tcg " - "-nodefaults -nographic " + "-nodefaults -serial null -nographic " "-drive if=pflash,format=raw,file=%s,readonly=on " "-drive if=pflash,format=raw,file=%s,snapshot=on %s", data->machine, data->machine_param ?: "", -- 2.51.0
