On 8/23/22 03:40, Xu, Min M wrote:
On August 23, 2022 3:38 PM, Gerd Hoffmann wrote:
Hi,
Ah, I forget to reserve the work-area as RT_Data in below code:
BuildMemoryAllocationHob (
(EFI_PHYSICAL_ADDRESS)(UINTN)FixedPcdGet32
(PcdOvmfWorkAreaBase),
(UINT64)(UINTN)FixedPcdGet32 (PcdOvmfWorkAreaSize),
PlatformInfoHob->S3Supported ? EfiACPIMemoryNVS :
EfiRuntimeServicesData <-- ACPI_NVS is not accessible either in OS-Runtime.
);
https://github.com/tianocore/edk2/blob/master/OvmfPkg/Library/Platform
InitLib/MemDetect.c#L1022-L1026
With that changed to use EfiRuntimeServicesData unconditionally the page
fault is gone.
Gerd, do you think we can reserve Ovmf WorkArea as RT_Data even when
S3 is supported?
Hmm, not fully sure how the various memory types are handled when the
VM is suspended.
Tom suggested that the work area should not be kept around. In stead a PCD
should be used.
https://edk2.groups.io/g/devel/message/92617
But the dynamic PCD is not thread-safe and it cannot be accessed by APs.
Now we have 2 solutions to fix this issue.
1. Reserve the Ovmf work area as RT_DATA.
2. Split the CcProbeLib into 2 instances. See
https://edk2.groups.io/g/devel/message/91132
Gerd & Tom, what's your thought?
Runtime service call are restricted so that you don't have concurrent
threads executing (see section 8.1 of the specification). Without that you
would have problems with runtime services today.
Thanks,
Tom
Thanks
Min
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