Re: [RFC PATCH 0/4] Confidential Guest Support: Introduce kvm_init() and kvm_reset() virtual functions

[Daniel P . Berrangé]

On Tue, Feb 06, 2024 at 03:28:48AM -0500, Xiaoyao Li wrote:
> This series is inspired and suggested by Daniel:
> https://lore.kernel.org/qemu-devel/ZbfoQsEuv6_zwl3b@redhat.com/
> 
> Currently, different confidential VMs in different architectures have
> their own specific *_kvm_init() (and some have *_kvm_reset()) exposed
> for KVM stuff when it's a confidential VM. e.g., sev_kmv_init() for x86
> SEV, pef_kvm_init() and pef_kvm_reset() for PPC PEF, and s390_pv_init()
> for s390 PV VMs.
> 
> Introduce a generic .kvm_init() and .kvm_reset() functions in
> ConfidentialGuestSupportClass, so that different cgs technologies in
> different architectures can implement their own, while common interface
> of cgs can be used.
> 
> This RFC implements two helper functions confidential_guest_kvm_init()
> and confidential_guest_kvm_reset() in Patch 1. In the following patches,
> they are called in arch specific implementation. X86 will benefit more
> for the generic implementation when TDX support is added.
> 
> There is one step forward possible, that calling
> confidential_guest_kvm_init() before kvm_arch_init() in kvm_int() in
> accel/kvm/kvm-all.c. This way, each arch doesn't need to call in their
> arch specific code.
> 
> X86 fits it, however I'm not sure if ppc and s390 fit it as well.
> Because currently, ppc calls it in machine->init()
> and s390 calls in MachineClass->init(). I'm not sure if there is any
> order dependency.

IIUC that s390 call is still a machine->init method, rather than
class init.

I think this series is nice, but its up to the KVM maintainers
to decide...


With regards,
Daniel
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