[PATCH v2 0/2] efi: Fixes for EFI_MEMORY_SP memory on RISC-V and ARM64

[PATCH v2 0/2] efi: Fixes for EFI_MEMORY_SP memory on RISC-V and ARM64

[Andrew Bresticker]

Two small fixes to enable the use soft-reserved/special-purpose memory
(EFI_MEMORY_SP) with dax_kmem on RISC-V (and ARM64, I think, though I
don't have a platform to test it on).

Patch 1 fixes a trivial integer narrowing bug. Patch 2 prevents adding
memblocks for soft-reserved memory so that it can later be hotplugged by
dax_kmem.

Tested on a RISC-V platform that presents a range of EFI_MEMORY_SP with
Bjorn's MEMORY_HOTPLUG series[0] applied.

[0]: https://lore.kernel.org/lkml/20230512145737.985671-1-bjorn@kernel.org/

v1->v2: address comments from Ard

Andrew Bresticker (2):
  efi: runtime: Fix potential overflow of soft-reserved region size
  efi: Don't add memblocks for soft-reserved memory

 drivers/firmware/efi/arm-runtime.c   |  2 +-
 drivers/firmware/efi/efi-init.c      | 19 ++++++++++---------
 drivers/firmware/efi/riscv-runtime.c |  2 +-
 3 files changed, 12 insertions(+), 11 deletions(-)

-- 
2.34.1

[PATCH v2 1/2] efi: runtime: Fix potential overflow of soft-reserved region size

[Andrew Bresticker]

md_size will have been narrowed if we have >= 4GB worth of pages in a
soft-reserved region.

Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
---
v2: use u64 instead of unsigned long
---
 drivers/firmware/efi/arm-runtime.c   | 2 +-
 drivers/firmware/efi/riscv-runtime.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
index 83f5bb57fa4c..83092d93f36a 100644
--- a/drivers/firmware/efi/arm-runtime.c
+++ b/drivers/firmware/efi/arm-runtime.c
@@ -107,7 +107,7 @@ static int __init arm_enable_runtime_services(void)
 		efi_memory_desc_t *md;
 
 		for_each_efi_memory_desc(md) {
-			int md_size = md->num_pages << EFI_PAGE_SHIFT;
+			u64 md_size = md->num_pages << EFI_PAGE_SHIFT;
 			struct resource *res;
 
 			if (!(md->attribute & EFI_MEMORY_SP))
diff --git a/drivers/firmware/efi/riscv-runtime.c b/drivers/firmware/efi/riscv-runtime.c
index 09525fb5c240..01f0f90ea418 100644
--- a/drivers/firmware/efi/riscv-runtime.c
+++ b/drivers/firmware/efi/riscv-runtime.c
@@ -85,7 +85,7 @@ static int __init riscv_enable_runtime_services(void)
 		efi_memory_desc_t *md;
 
 		for_each_efi_memory_desc(md) {
-			int md_size = md->num_pages << EFI_PAGE_SHIFT;
+			u64 md_size = md->num_pages << EFI_PAGE_SHIFT;
 			struct resource *res;
 
 			if (!(md->attribute & EFI_MEMORY_SP))
-- 
2.34.1

[PATCH v2 2/2] efi: Don't add memblocks for soft-reserved memory

[Andrew Bresticker]

Adding memblocks for soft-reserved regions prevents them from later being
hotplugged in by dax_kmem.

Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
---
v2: only skip adding memblocks for soft-reserved mem
---
 drivers/firmware/efi/efi-init.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/firmware/efi/efi-init.c b/drivers/firmware/efi/efi-init.c
index d4987d013080..a00e07b853f2 100644
--- a/drivers/firmware/efi/efi-init.c
+++ b/drivers/firmware/efi/efi-init.c
@@ -143,15 +143,6 @@ static __init int is_usable_memory(efi_memory_desc_t *md)
 	case EFI_BOOT_SERVICES_DATA:
 	case EFI_CONVENTIONAL_MEMORY:
 	case EFI_PERSISTENT_MEMORY:
-		/*
-		 * Special purpose memory is 'soft reserved', which means it
-		 * is set aside initially, but can be hotplugged back in or
-		 * be assigned to the dax driver after boot.
-		 */
-		if (efi_soft_reserve_enabled() &&
-		    (md->attribute & EFI_MEMORY_SP))
-			return false;
-
 		/*
 		 * According to the spec, these regions are no longer reserved
 		 * after calling ExitBootServices(). However, we can only use
@@ -196,6 +187,16 @@ static __init void reserve_regions(void)
 		size = npages << PAGE_SHIFT;
 
 		if (is_memory(md)) {
+			/*
+			 * Special purpose memory is 'soft reserved', which
+			 * means it is set aside initially. Don't add a memblock
+			 * for it now so that it can be hotplugged back in or
+			 * be assigned to the dax driver after boot.
+			 */
+			if (efi_soft_reserve_enabled() &&
+			    (md->attribute & EFI_MEMORY_SP))
+				continue;
+
 			early_init_dt_add_memory_arch(paddr, size);
 
 			if (!is_usable_memory(md))
-- 
2.34.1

Re: [PATCH v2 0/2] efi: Fixes for EFI_MEMORY_SP memory on RISC-V and ARM64

[Ard Biesheuvel]

On Fri, 2 Feb 2024 at 19:07, Andrew Bresticker <abrestic@rivosinc.com> wrote:
>
> Two small fixes to enable the use soft-reserved/special-purpose memory
> (EFI_MEMORY_SP) with dax_kmem on RISC-V (and ARM64, I think, though I
> don't have a platform to test it on).
>
> Patch 1 fixes a trivial integer narrowing bug. Patch 2 prevents adding
> memblocks for soft-reserved memory so that it can later be hotplugged by
> dax_kmem.
>
> Tested on a RISC-V platform that presents a range of EFI_MEMORY_SP with
> Bjorn's MEMORY_HOTPLUG series[0] applied.
>
> [0]: https://lore.kernel.org/lkml/20230512145737.985671-1-bjorn@kernel.org/
>
> v1->v2: address comments from Ard
>
> Andrew Bresticker (2):
>   efi: runtime: Fix potential overflow of soft-reserved region size
>   efi: Don't add memblocks for soft-reserved memory
>

Thanks, I'll take these both as fixes.

Re: [PATCH v2 0/2] efi: Fixes for EFI_MEMORY_SP memory on RISC-V and ARM64

[Palmer Dabbelt]

On Fri, 02 Feb 2024 10:28:54 PST (-0800), Ard Biesheuvel wrote:
> On Fri, 2 Feb 2024 at 19:07, Andrew Bresticker <abrestic@rivosinc.com> wrote:
>>
>> Two small fixes to enable the use soft-reserved/special-purpose memory
>> (EFI_MEMORY_SP) with dax_kmem on RISC-V (and ARM64, I think, though I
>> don't have a platform to test it on).
>>
>> Patch 1 fixes a trivial integer narrowing bug. Patch 2 prevents adding
>> memblocks for soft-reserved memory so that it can later be hotplugged by
>> dax_kmem.
>>
>> Tested on a RISC-V platform that presents a range of EFI_MEMORY_SP with
>> Bjorn's MEMORY_HOTPLUG series[0] applied.
>>
>> [0]: https://lore.kernel.org/lkml/20230512145737.985671-1-bjorn@kernel.org/
>>
>> v1->v2: address comments from Ard
>>
>> Andrew Bresticker (2):
>>   efi: runtime: Fix potential overflow of soft-reserved region size
>>   efi: Don't add memblocks for soft-reserved memory
>>
>
> Thanks, I'll take these both as fixes.

Acked-by: Palmer Dabbelt <palmer@rivosinc.com>

Thanks!