When EFI_UNACCEPTED_MEMORY is present in the EFI memory map or the platform supports dynamic memory unacceptance (such as AMD SEV-SNP), start the EFI unaccepted memory bitmap at physical address 0 (phys_base = 0) instead of the lowest initial unaccepted address.
This ensures that pre-accepted low memory below the initial unaccepted region is addressable in the bitmap so it can be dynamically marked unaccepted and re-accepted later via virtio-balloon or free page reporting. Non-confidential guests without EFI_UNACCEPTED_MEMORY continue to skip allocating the table. Signed-off-by: Kevin Loughlin <[email protected]> --- .../firmware/efi/libstub/unaccepted_memory.c | 45 ++++++++++++++----- 1 file changed, 33 insertions(+), 12 deletions(-) diff --git a/drivers/firmware/efi/libstub/unaccepted_memory.c b/drivers/firmware/efi/libstub/unaccepted_memory.c index 757dbe734a47..fcb622ac0564 100644 --- a/drivers/firmware/efi/libstub/unaccepted_memory.c +++ b/drivers/firmware/efi/libstub/unaccepted_memory.c @@ -2,15 +2,28 @@ #include <linux/efi.h> #include <asm/efi.h> +#if defined(CONFIG_X86) && defined(CONFIG_AMD_MEM_ENCRYPT) +#include <asm/sev.h> +#endif #include "efistub.h" struct efi_unaccepted_memory *unaccepted_table; +static bool efi_stub_has_dynamic_unaccepted_memory(void) +{ +#if defined(CONFIG_X86) && defined(CONFIG_AMD_MEM_ENCRYPT) + return sev_get_status() & MSR_AMD64_SEV_SNP_ENABLED; +#else + return false; +#endif +} + efi_status_t allocate_unaccepted_bitmap(__u32 nr_desc, struct efi_boot_memmap *map) { efi_guid_t unaccepted_table_guid = LINUX_EFI_UNACCEPTED_MEM_TABLE_GUID; - u64 unaccepted_start = ULLONG_MAX, unaccepted_end = 0, bitmap_size; + bool has_unaccepted = efi_stub_has_dynamic_unaccepted_memory(); + u64 unaccepted_end = 0, bitmap_size; efi_status_t status; int i; @@ -30,19 +43,27 @@ efi_status_t allocate_unaccepted_bitmap(__u32 nr_desc, unsigned long m = (unsigned long)map->map; d = efi_memdesc_ptr(m, map->desc_size, i); - if (d->type != EFI_UNACCEPTED_MEMORY) - continue; - - unaccepted_start = min(unaccepted_start, d->phys_addr); - unaccepted_end = max(unaccepted_end, - d->phys_addr + d->num_pages * PAGE_SIZE); + switch (d->type) { + case EFI_UNACCEPTED_MEMORY: + has_unaccepted = true; + fallthrough; + case EFI_LOADER_CODE: + case EFI_LOADER_DATA: + case EFI_BOOT_SERVICES_CODE: + case EFI_BOOT_SERVICES_DATA: + case EFI_CONVENTIONAL_MEMORY: + unaccepted_end = max(unaccepted_end, + d->phys_addr + + d->num_pages * EFI_PAGE_SIZE); + break; + default: + break; + } } - if (unaccepted_start == ULLONG_MAX) + if (!has_unaccepted || unaccepted_end == 0) return EFI_SUCCESS; - unaccepted_start = round_down(unaccepted_start, - EFI_UNACCEPTED_UNIT_SIZE); unaccepted_end = round_up(unaccepted_end, EFI_UNACCEPTED_UNIT_SIZE); /* @@ -59,7 +80,7 @@ efi_status_t allocate_unaccepted_bitmap(__u32 nr_desc, * The bitmap will be populated in setup_e820() according to the memory * map after efi_exit_boot_services(). */ - bitmap_size = DIV_ROUND_UP(unaccepted_end - unaccepted_start, + bitmap_size = DIV_ROUND_UP(unaccepted_end, EFI_UNACCEPTED_UNIT_SIZE * BITS_PER_BYTE); status = efi_bs_call(allocate_pool, EFI_ACPI_RECLAIM_MEMORY, @@ -72,7 +93,7 @@ efi_status_t allocate_unaccepted_bitmap(__u32 nr_desc, unaccepted_table->version = 1; unaccepted_table->unit_size = EFI_UNACCEPTED_UNIT_SIZE; - unaccepted_table->phys_base = unaccepted_start; + unaccepted_table->phys_base = 0; unaccepted_table->size = bitmap_size; memset(unaccepted_table->bitmap, 0, bitmap_size); -- 2.56.0.307.g5fe7bd680c-goog
