Public bug reported:

The firmware descriptor file installed by the current ovmf-amdsev
package (2025.11-3ubuntu7) contains the following content.

/usr/share/qemu/firmware/60-edk2-x86_64-amdsev.json
---
{
    "description": "UEFI firmware for x86_64, with SEV-ES support",
    "interface-types": [
        "uefi"
    ],
    "mapping": {
        "device": "flash",
        "mode": "stateless",
        "executable": {
            "filename": "/usr/share/ovmf/OVMF.amdsev.fd",
            "format": "raw"
        }
    },
    "targets": [
        {
            "architecture": "x86_64",
            "machines": [
                "pc-q35-*"
            ]
        }
    ],
    "features": [
        "amd-sev",
        "amd-sev-es",
        "amd-sev-snp",
        "verbose-dynamic"
    ],
    "tags": [

    ]
}
---

Although "amd-sev-snp" appears in its feature list, this descriptor is not 
compatible with SEV-SNP because only the rom type firmware is accepted.
When an instance is created with SEV-SNP encryption and libvirt selects this 
firmware, qemu fails to start due to the error "pflash with kvm requires KVM 
readonly memory support".

To allow SEV-SNP instances launch properly, the mapping field should be
updated to:

---
    ...
    "mapping": {
        "device": "memory",
        "filename": "/usr/share/edk2/ovmf/OVMF.amdsev.fd"

    },
    ...
---

Note:
That "device": "memory" is the flag to tell libvirt to use the -bios option in 
qemu, which is described in the qemu command line example in 
https://ubuntu.com/server/docs/how-to/virtualisation/sev-snp/#host-configuration
 .

** Affects: edk2 (Ubuntu)
     Importance: Undecided
         Status: New

** Bug watch added: github.com/AMDESE/AMDSEV/issues #236
   https://github.com/AMDESE/AMDSEV/issues/236

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https://bugs.launchpad.net/bugs/2160129

Title:
  Descriptor file for amd-sev is not compatible with SEV-SNP

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