From 413a67450750e0459efeffc3db3ba9759c3e381c Mon Sep 17 00:00:00 2001 From: Michael Roth Date: Thu, 30 May 2024 06:16:39 -0500 Subject: [PATCH] hw/i386/sev: Use guest_memfd for legacy ROMs Current SNP guest kernels will attempt to access these regions with with C-bit set, so guest_memfd is needed to handle that. Otherwise, kvm_convert_memory() will fail when the guest kernel tries to access it and QEMU attempts to call KVM_SET_MEMORY_ATTRIBUTES to set these ranges to private. Whether guests should actually try to access ROM regions in this way (or need to deal with legacy ROM regions at all), is a separate issue to be addressed on kernel side, but current SNP guest kernels will exhibit this behavior and so this handling is needed to allow QEMU to continue running existing SNP guest kernels. Signed-off-by: Michael Roth [pankaj: Added sev_snp_enabled() check] Signed-off-by: Pankaj Gupta Message-ID: <20240530111643.1091816-28-pankaj.gupta@amd.com> Signed-off-by: Paolo Bonzini --- hw/i386/pc.c | 14 ++++++++++---- hw/i386/pc_sysfw.c | 19 +++++++++++++------ 2 files changed, 23 insertions(+), 10 deletions(-) diff --git a/hw/i386/pc.c b/hw/i386/pc.c index 7b638da7aa..0469af00a7 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -62,6 +62,7 @@ #include "hw/mem/memory-device.h" #include "e820_memory_layout.h" #include "trace.h" +#include "sev.h" #include CONFIG_DEVICES #ifdef CONFIG_XEN_EMU @@ -1022,10 +1023,15 @@ void pc_memory_init(PCMachineState *pcms, pc_system_firmware_init(pcms, rom_memory); option_rom_mr = g_malloc(sizeof(*option_rom_mr)); - memory_region_init_ram(option_rom_mr, NULL, "pc.rom", PC_ROM_SIZE, - &error_fatal); - if (pcmc->pci_enabled) { - memory_region_set_readonly(option_rom_mr, true); + if (machine_require_guest_memfd(machine)) { + memory_region_init_ram_guest_memfd(option_rom_mr, NULL, "pc.rom", + PC_ROM_SIZE, &error_fatal); + } else { + memory_region_init_ram(option_rom_mr, NULL, "pc.rom", PC_ROM_SIZE, + &error_fatal); + if (pcmc->pci_enabled) { + memory_region_set_readonly(option_rom_mr, true); + } } memory_region_add_subregion_overlap(rom_memory, PC_ROM_MIN_VGA, diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c index 7cdbafc8d2..ef80281d28 100644 --- a/hw/i386/pc_sysfw.c +++ b/hw/i386/pc_sysfw.c @@ -40,8 +40,8 @@ #define FLASH_SECTOR_SIZE 4096 -static void pc_isa_bios_init(MemoryRegion *isa_bios, MemoryRegion *rom_memory, - MemoryRegion *flash_mem) +static void pc_isa_bios_init(PCMachineState *pcms, MemoryRegion *isa_bios, + MemoryRegion *rom_memory, MemoryRegion *flash_mem) { int isa_bios_size; uint64_t flash_size; @@ -51,8 +51,13 @@ static void pc_isa_bios_init(MemoryRegion *isa_bios, MemoryRegion *rom_memory, /* map the last 128KB of the BIOS in ISA space */ isa_bios_size = MIN(flash_size, 128 * KiB); - memory_region_init_ram(isa_bios, NULL, "isa-bios", isa_bios_size, - &error_fatal); + if (machine_require_guest_memfd(MACHINE(pcms))) { + memory_region_init_ram_guest_memfd(isa_bios, NULL, "isa-bios", + isa_bios_size, &error_fatal); + } else { + memory_region_init_ram(isa_bios, NULL, "isa-bios", isa_bios_size, + &error_fatal); + } memory_region_add_subregion_overlap(rom_memory, 0x100000 - isa_bios_size, isa_bios, @@ -65,7 +70,9 @@ static void pc_isa_bios_init(MemoryRegion *isa_bios, MemoryRegion *rom_memory, ((uint8_t*)flash_ptr) + (flash_size - isa_bios_size), isa_bios_size); - memory_region_set_readonly(isa_bios, true); + if (!machine_require_guest_memfd(current_machine)) { + memory_region_set_readonly(isa_bios, true); + } } static PFlashCFI01 *pc_pflash_create(PCMachineState *pcms, @@ -191,7 +198,7 @@ static void pc_system_flash_map(PCMachineState *pcms, x86_isa_bios_init(&x86ms->isa_bios, rom_memory, flash_mem, true); } else { - pc_isa_bios_init(&x86ms->isa_bios, rom_memory, flash_mem); + pc_isa_bios_init(pcms, &x86ms->isa_bios, rom_memory, flash_mem); } /* Encrypt the pflash boot ROM */