On 6/10/21 6:44 AM, Ming Huang via groups.io wrote:

On 6/9/21 3:10 PM, Ard Biesheuvel wrote:

On Tue, 8 Jun 2021 at 16:21, Ming Huang <huangming@...>

wrote:

TF-A: TrustedFirmware-a
SPM: Secure Partition Manager(MM)

For AArch64, when SPM enable in TF-A, TF-A may communicate to MM

with

buffer address (PLAT_SPM_BUF_BASE). The address is different from
PcdMmBufferBase which use in edk2.

Then why do we have PcdMmBufferBase?

ArmPkg use this Pcd for the base address of non-secure communication
buffer.

Is it possible to set PcdMmBufferBase to the correct value?

The secure communication may interrupt the non-secure communication. if
we use the same address (PcdMmBufferBase and PLAT_SPM_BUF_BASE), the
date in communication buffer may be corrupted.

Best Regards,
Ming

In case where an interrupt handler executing from EL3 makes a call into StandaloneMM, the handler in EL3 makes an spm call into StandaloneMM using PLAT_SPM_BUF_BASE buffer base address. This PLAT_SPM_BUF_BASE is a shared buffer between EL3 and S-EL0. This is where the following check fails and leads to spm call failure. So this change would help resolve this issue.

- Omkar

Checking address will let TF-A communicate failed to MM. So remove
below checking code:
if (NsCommBufferAddr < mNsCommBuffer.PhysicalStart) {
return EFI_ACCESS_DENIED;
}

Signed-off-by: Ming Huang <huangming@...>
---
StandaloneMmPkg/Drivers/StandaloneMmCpu/AArch64/EventHandle.c |

4

----
1 file changed, 4 deletions(-)

diff --git
a/StandaloneMmPkg/Drivers/StandaloneMmCpu/AArch64/EventHandle.c
b/StandaloneMmPkg/Drivers/StandaloneMmCpu/AArch64/EventHandle.c
index 63fbe26642..fe98d3181d 100644
---

a/StandaloneMmPkg/Drivers/StandaloneMmCpu/AArch64/EventHandle.c

+++

b/StandaloneMmPkg/Drivers/StandaloneMmCpu/AArch64/EventHandle.c

@@ -103,10 +103,6 @@ PiMmStandaloneArmTfCpuDriverEntry (
return EFI_INVALID_PARAMETER;
}

- if (NsCommBufferAddr < mNsCommBuffer.PhysicalStart) {
- return EFI_ACCESS_DENIED;
- }
-
if ((NsCommBufferAddr + sizeof (EFI_MM_COMMUNICATE_HEADER)) >=
(mNsCommBuffer.PhysicalStart + mNsCommBuffer.PhysicalSize)) {
return EFI_INVALID_PARAMETER;
--
2.17.1