[PATCHv2] arm64: efi: correctly map runtime regions

[Mark Rutland]

The kernel may use a page granularity of 4K, 16K, or 64K depending on
configuration.

When mapping EFI runtime regions, we use memrange_efi_to_native to round
the physical base address of a region down to a kernel page boundary,
and round the size up to a kernel page boundary, adding the residue left
over from rounding down the physical base address. We do not round down
the virtual base address.

In __create_mapping we account for the offset of the virtual base from a
granule boundary, adding the residue to the size before rounding the
base down to said granule boundary.

Thus we account for the residue twice, and when the residue is non-zero
will cause __create_mapping to map an additional page at the end of the
region. Depending on the memory map, this page may be in a region we are
not intended/permitted to map, or may clash with a different region that
we which to map.

As __create_mapping can cope with base addresses which are not page
aligned, we can instead rely on it to map the region appropriately, and
simplify efi_virtmap_init by removing the unnecessary code.

Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Leif Lindholm <leif.lindholm at linaro.org>
Cc: Will Deacon <will.deacon at arm.com>
---
 arch/arm64/kernel/efi.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index de46b50..25b82d8 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -225,7 +225,7 @@ static bool __init efi_virtmap_init(void)
 	efi_memory_desc_t *md;
 
 	for_each_efi_memory_desc(&memmap, md) {
-		u64 paddr, npages, size;
+		u64 size;
 		pgprot_t prot;
 
 		if (!(md->attribute & EFI_MEMORY_RUNTIME))
@@ -233,10 +233,7 @@ static bool __init efi_virtmap_init(void)
 		if (md->virt_addr == 0)
 			return false;
 
-		paddr = md->phys_addr;
-		npages = md->num_pages;
-		memrange_efi_to_native(&paddr, &npages);
-		size = npages << PAGE_SHIFT;
+		size = md->num_pages << EFI_PAGE_SHIFT;
 
 		pr_info("  EFI remap 0x%016llx => %p\n",
 			md->phys_addr, (void *)md->virt_addr);
@@ -254,7 +251,8 @@ static bool __init efi_virtmap_init(void)
 		else
 			prot = PAGE_KERNEL;
 
-		create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot);
+		create_pgd_mapping(&efi_mm, md->phys_addr, md->virt_addr,
+				   size, prot);
 	}
 	return true;
 }
-- 
1.9.1