Messages in this thread |  | | Date | Wed, 28 May 2025 09:38:24 +0200 | | From | Gerd Hoffmann <> | | Subject | Re: [PATCH 1/2] x86/sev/vc: fix efi runtime instruction emulation |
| |
On Tue, May 27, 2025 at 06:21:51PM +0200, Borislav Petkov wrote: > On Tue, May 27, 2025 at 04:45:44PM +0200, Gerd Hoffmann wrote: > > In case efi_mm is active go use the userspace instruction decoder which > > supports fetching instructions from active_mm. This is needed to make > > instruction emulation work for EFI runtime code, so it can use cpuid > > and rdmsr. > > > > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> > > --- > > arch/x86/coco/sev/core.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > Can you pls explain what the use cases for this and your next patch are?
Use case is coconut-svsm providing an uefi variable store and edk2 runtime code doing svsm protocol calls to send requests to the svsm variable store. edk2 needs a caa page mapping and a working rdmsr instruction for that.
Another less critical but useful case is edk2 debug logging to qemu debugcon port. That needs a working cpuid instruction because edk2 uses that to figure whenever sev is active and adapt ioport access accordingly.
> We'd like to add them to our test pile.
That is a bit difficult right now because there are a number of pieces which need to fall into place before this is easily testable. You need:
* host kernel with vmplanes patch series (for snp vmpl support). * coconut svsm with uefi variable store patches. * edk2 patches so it talks to svsm for variable access. * igvm support patches for qemu.
Hope I didn't forgot something ...
take care, Gerd
|  |