On 15/5/25 18:18, Zhi Wang wrote:
On Tue, 18 Feb 2025 22:10:02 +1100 Alexey Kardashevskiy <aik@xxxxxxx> wrote:Currently private MMIO nested page faults are not expected so when such fault occurs, KVM tries moving the faulted page from private to shared which is not going to work as private MMIO is not backed by memfd. Handle private MMIO as shared: skip page state change and memfd page state tracking. The MMIO KVM memory slot is still marked as shared as the guest can access it as private or shared so marking the MMIO slot as private is not going to help. Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxx> --- arch/x86/kvm/mmu/mmu.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 74c20dbb92da..32e27080b1c7 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4347,7 +4347,11 @@ static int __kvm_mmu_faultin_pfn(struct kvm_vcpu *vcpu, { unsigned int foll = fault->write ? FOLL_WRITE : 0;- if (fault->is_private)+ if (fault->slot && fault->is_private && !kvm_slot_can_be_private(fault->slot) && + (vcpu->kvm->arch.vm_type == KVM_X86_SNP_VM)) + pr_warn("%s: private SEV TIO MMIO fault for fault->gfn=%llx\n", + __func__, fault->gfn); + else if (fault->is_private) return kvm_mmu_faultin_pfn_private(vcpu, fault);Let's fold this in a macro and make this more informative with comments.
Rather than this, https://lore.kernel.org/r/20250107142719.179636-1-yilun.xu@xxxxxxxxxxxxxxx seems to be the way to go. Thanks,
foll |= FOLL_NOWAIT;
-- Alexey
