Re: [edk2-devel] [PATCH 5/7] OvmfPkg/VirtNorFlashDxe: Not add memory space if it exists

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

On Mon, 6 Mar 2023 at 18:33, Tuan Phan <tphan@ventanamicro.com> wrote:
>
> The flash base address can be added to GCD before this driver run.
> So only add it if it has not been done.
>

How do you end up in this situation?

You cannot skip this registration, as it is required to get the region
marked as EFI_MEMORY_RUNTIME, and without that, EFI variables will be
broken when running under the OS.

> Signed-off-by: Tuan Phan <tphan@ventanamicro.com>
> ---
>  OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.c | 25 +++++++++++++++--------
>  1 file changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.c b/OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.c
> index f9a41f6aab0f..8875824f3333 100644
> --- a/OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.c
> +++ b/OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.c
> @@ -372,10 +372,11 @@ NorFlashFvbInitialize (
>    IN NOR_FLASH_INSTANCE  *Instance
>    )
>  {
> -  EFI_STATUS     Status;
> -  UINT32         FvbNumLba;
> -  EFI_BOOT_MODE  BootMode;
> -  UINTN          RuntimeMmioRegionSize;
> +  EFI_STATUS                      Status;
> +  UINT32                          FvbNumLba;
> +  EFI_BOOT_MODE                   BootMode;
> +  UINTN                           RuntimeMmioRegionSize;
> +  EFI_GCD_MEMORY_SPACE_DESCRIPTOR Desc;
>
>    DEBUG ((DEBUG_BLKIO, "NorFlashFvbInitialize\n"));
>    ASSERT ((Instance != NULL));
> @@ -390,13 +391,19 @@ NorFlashFvbInitialize (
>    //       is written as the base of the flash region (ie: Instance->DeviceBaseAddress)
>    RuntimeMmioRegionSize = (Instance->RegionBaseAddress - Instance->DeviceBaseAddress) + Instance->Size;
>
> -  Status = gDS->AddMemorySpace (
> -                  EfiGcdMemoryTypeMemoryMappedIo,
> +  Status = gDS->GetMemorySpaceDescriptor (
>                    Instance->DeviceBaseAddress,
> -                  RuntimeMmioRegionSize,
> -                  EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
> +                  &Desc
>                    );
> -  ASSERT_EFI_ERROR (Status);
> +  if (Status == EFI_NOT_FOUND) {
> +    Status = gDS->AddMemorySpace (
> +                    EfiGcdMemoryTypeMemoryMappedIo,
> +                    Instance->DeviceBaseAddress,
> +                    RuntimeMmioRegionSize,
> +                    EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
> +                    );
> +    ASSERT_EFI_ERROR (Status);
> +  }
>
>    Status = gDS->SetMemorySpaceAttributes (
>                    Instance->DeviceBaseAddress,
> --
> 2.25.1
>
>
>
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