Re: [PATCH v9 30/32] OvmfPkg/PlatformPei: mark cpuid and secrets memory reserved in EFI map

Brijesh Singh

On 10/14/21 1:58 AM, Gerd Hoffmann wrote:
On Wed, Oct 13, 2021 at 11:57:11AM -0500, Brijesh Singh wrote:
When SEV-SNP is active, the CPUID and Secrets memory range contains the
information that is used during the VM boot. The content need to be persist
across the kexec boot. Mark the memory range as Reserved in the EFI map
so that guest OS or firmware does not use the range as a system RAM.
Why is this needed? Isn't the complete firmware memory tagged as
reserved anyway?
PlatformPei detects all the guest memory and marks it as a SYSTEM_RAM
unless its an MMIO or added as reserved in e820 map file. Since the
Secrets and CPUID pages are part of system RAM so we need to explicitly
exclude these region.


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