On Mon, Aug 23, 2021 at 05:30:54PM -0700, Kuppuswamy, Sathyanarayanan wrote: > > > On 8/23/21 4:56 PM, Michael S. Tsirkin wrote: > > > Add a new variant of pci_iomap for mapping all PCI resources > > > of a devices as shared memory with a hypervisor in a confidential > > > guest. > > > > > > Signed-off-by: Andi Kleen<ak@xxxxxxxxxxxxxxx> > > > Signed-off-by: Kuppuswamy Sathyanarayanan<sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> > > I'm a bit puzzled by this part. So why should the guest*not* map > > pci memory as shared? And if the answer is never (as it seems to be) > > then why not just make regular pci_iomap DTRT? > > It is in the context of confidential guest (where VMM is un-trusted). So > we don't want to make all PCI resource as shared. It should be allowed > only for hardened drivers/devices. I can't say this answers the question at all. PCI devices are part of the VMM and so un-trusted. In particular PCI devices do not have the key to decrypt memory. Therefore as far as I can see PCI resources should not be encrypted. I conclude they all should be marked shared. If I'm wrong can you please give an example of a PCI resource that is encrypted? -- MST
