From: Michael Roth <michael.roth@xxxxxxx>
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 <michael.roth@xxxxxxx>
[pankaj: Added sev_snp_enabled() check]
Signed-off-by: Pankaj Gupta <pankaj.gupta@xxxxxxx>
---
hw/i386/pc.c | 14 ++++++++++----
hw/i386/pc_sysfw.c | 13 ++++++++++---
2 files changed, 20 insertions(+), 7 deletions(-)
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 7b638da7aa..62c25ea1e9 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 (sev_snp_enabled()) {
+ 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 00464afcb4..def77a442d 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -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 (sev_snp_enabled()) {
+ 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,
--
2.34.1
