Re: [RFC PATCH 6/8] KVM: x86: Implement kvm_arch_{, pre_}vcpu_map_memory()

Isaku Yamahata
2024-03-07T01:34:53Z

On Wed, Mar 06, 2024 at 04:30:58PM -0800,
David Matlack <dmatlack@google.com> wrote:

> On 2024-03-01 09:28 AM, isaku.yamahata@intel.com wrote:
> > From: Isaku Yamahata <isaku.yamahata@intel.com>
> >
> > Wire KVM_MAP_MEMORY ioctl to kvm_mmu_map_tdp_page() to populate guest
> > memory.
> >
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> > ---
> > arch/x86/kvm/x86.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 49 insertions(+)
> >
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 3b8cb69b04fa..6025c0e12d89 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -4660,6 +4660,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> > case KVM_CAP_VM_DISABLE_NX_HUGE_PAGES:
> > case KVM_CAP_IRQFD_RESAMPLE:
> > case KVM_CAP_MEMORY_FAULT_INFO:
> > + case KVM_CAP_MAP_MEMORY:
> > r = 1;
> > break;
> > case KVM_CAP_EXIT_HYPERCALL:
> > @@ -5805,6 +5806,54 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
> > }
> > }
> >
> > +int kvm_arch_vcpu_pre_map_memory(struct kvm_vcpu *vcpu)
> > +{
> > + return kvm_mmu_reload(vcpu);
> > +}
>
> Why is the here and not kvm_arch_vcpu_map_memory()?

We can push down kvm_mmu_relaod into kvm_arch_vcpu_map_memory() under gpa loop.
Probably the inefficiency won't matter.

kvm_mmu_realod()
loop on gpa
kvm_arch_vcpu_map_memory()

=>

loop on gpa
kvm_arch_vcpu_map_memory()
kvm_mmu_reload()
--
Isaku Yamahata <isaku.yamahata@linux.intel.com>