On Fri, Jan 27, 2023 at 08:35:58AM -0800, Jeremi Piotrowski wrote: > On Wed, Dec 14, 2022 at 01:39:59PM -0600, Michael Roth wrote: > > From: Nikunj A Dadhania <nikunj@xxxxxxx> > > > > KVM_HC_MAP_GPA_RANGE hypercall is used by the SEV guest to notify a > > change in the page encryption status to the hypervisor. > > > > The hypercall exits to userspace with KVM_EXIT_HYPERCALL exit code, > > currently this is used for explicit memory conversion between > > shared/private for memfd based private memory. > > > > Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx> > > Signed-off-by: Michael Roth <michael.roth@xxxxxxx> > > --- > > arch/x86/kvm/x86.c | 8 ++++++++ > > virt/kvm/kvm_main.c | 1 + > > 2 files changed, 9 insertions(+) > > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index bb6adb216054..732f9cbbadb5 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -9649,6 +9649,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) > > Couldn't find a better commit to comment on: > when the guest has the ptp-kvm module, it will issue a KVM_HC_CLOCK_PAIRING > hypercall. This will pass sev_es_validate_vmgexit validation and end up in this > function where kvm_pv_clock_pairing() is called, and that calls > kvm_write_guest(). This results in a CPU soft-lockup, at least in my testing. > > Are there any emulated hypercalls that make sense for snp guests? We should > block at least the ones that definitely don't work. > > Jeremi So turns out the soft-lockup is a nested issue (details here for those interested: [^1]), but the questions still stands, of whether we should block kvm_write_page (and similar) explicitly or rely on the rmp fault. [^1]: https://github.com/jepio/linux/commit/6c3bdf552e93664ae172660e24ceceed60fd4df5
