[PATCH] ACPI: PRM: Fix off-by-one in efi_pa_va_lookup() address range check

[Guanghui Feng]

The boundary check in efi_pa_va_lookup() uses a strict less-than
comparison (md->phys_addr < pa), which incorrectly excludes the case
where the lookup address equals the start of an EFI memory descriptor's
physical address range.

This causes a lookup failure when a PRM handler address happens to be
at the exact start of a runtime memory region, as the descriptor that
should match gets skipped.

Fix this by using a non-strict comparison (md->phys_addr <= pa) to
include the region start address, consistent with the standard
__efi_mem_desc_lookup() implementation in drivers/firmware/efi/efi.c.

Fixes: cefc7ca46235 ("ACPI: PRM: implement OperationRegion handler for the PlatformRtMechanism subtype")
Signed-off-by: Guanghui Feng <guanghui.fgh@xxxxxxxxxxxxxxxxx>
---
 drivers/acpi/prmt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/prmt.c b/drivers/acpi/prmt.c
index 7f5851371e5f..fcc17ce0a88e 100644
--- a/drivers/acpi/prmt.c
+++ b/drivers/acpi/prmt.c
@@ -80,7 +80,7 @@ static u64 efi_pa_va_lookup(efi_guid_t *guid, u64 pa)
 
 	for_each_efi_memory_desc(md) {
 		if ((md->attribute & EFI_MEMORY_RUNTIME) &&
-		    (md->phys_addr < pa && pa < md->phys_addr + PAGE_SIZE * md->num_pages)) {
+		    (md->phys_addr <= pa && pa < md->phys_addr + PAGE_SIZE * md->num_pages)) {
 			return pa_offset + md->virt_addr + page - md->phys_addr;
 		}
 	}
-- 
2.43.7