Re: [PATCH 1/1] OvmfPkg/VirtNorFlashDxe: map flash memory as uncacheable

["Ard Biesheuvel" <ardb@kernel.org>]

On Wed, 11 Jan 2023 at 19:00, Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> Switching from the ArmPlatformPkg/NorFlashDxe driver to the
> OvmfPkg/VirtNorFlashDxe driver had the side effect that flash address
> space got registered as EFI_MEMORY_WC instead of EFI_MEMORY_UC.
>
> That confuses the linux kernel's numa code, seems this makes kernel
> consider the flash being node memory.  "lsmem" changes from ...
>
>     RANGE                                 SIZE  STATE REMOVABLE BLOCK
>     0x0000000040000000-0x000000013fffffff   4G online       yes  8-39
>
> ... to ...
>
>     RANGE                                  SIZE  STATE REMOVABLE BLOCK
>     0x0000000000000000-0x0000000007ffffff  128M online       yes     0
>     0x0000000040000000-0x000000013fffffff    4G online       yes  8-39
>
> ... and in the kernel log got new error lines:
>
>     NUMA: Warning: invalid memblk node 512 [mem 0x0000000004000000-0x0000000007ffffff]
>     NUMA: Faking a node at [mem 0x0000000004000000-0x000000013fffffff]
>
> Changing the attributes back to EFI_MEMORY_UC fixes this.
>
> Fixes: b92298af8218 ("ArmVirtPkg/ArmVirtQemu: migrate to OVMF's VirtNorFlashDxe")
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

Queued up as #3887

> ---
>  OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.c b/OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.c
> index ff3121af2a40..f9a41f6aab0f 100644
> --- a/OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.c
> +++ b/OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.c
> @@ -394,14 +394,14 @@ NorFlashFvbInitialize (
>                    EfiGcdMemoryTypeMemoryMappedIo,
>                    Instance->DeviceBaseAddress,
>                    RuntimeMmioRegionSize,
> -                  EFI_MEMORY_WC | EFI_MEMORY_RUNTIME
> +                  EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
>                    );
>    ASSERT_EFI_ERROR (Status);
>
>    Status = gDS->SetMemorySpaceAttributes (
>                    Instance->DeviceBaseAddress,
>                    RuntimeMmioRegionSize,
> -                  EFI_MEMORY_WC | EFI_MEMORY_RUNTIME
> +                  EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
>                    );
>    ASSERT_EFI_ERROR (Status);
>
> --
> 2.39.0
>