Re: [PATCH v7 048/102] KVM: x86/mmu: Disallow dirty logging for x86 TDX

Kai Huang
2022-07-08T02:30:38Z

On Mon, 2022-06-27 at 14:53 -0700, isaku.yamahata@intel.com wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
>
> TDX doesn't support dirty logging. Report dirty logging isn't supported so
> that device model, for example qemu, can properly handle it.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>

Xiaoyao's SoB looks weird.

> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> arch/x86/kvm/x86.c | 5 +++++
> include/linux/kvm_host.h | 1 +
> virt/kvm/kvm_main.c | 15 ++++++++++++---
> 3 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 4309ef0ade21..dcd1f5e2ba05 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -13164,6 +13164,11 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size,
> }
> EXPORT_SYMBOL_GPL(kvm_sev_es_string_io);
>
> +bool kvm_arch_dirty_log_supported(struct kvm *kvm)
> +{
> + return kvm->arch.vm_type != KVM_X86_TDX_VM;
> +}
> +
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_entry);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 79a4988fd51f..6fd8ec297236 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1452,6 +1452,7 @@ bool kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu *vcpu);
> int kvm_arch_post_init_vm(struct kvm *kvm);
> void kvm_arch_pre_destroy_vm(struct kvm *kvm);
> int kvm_arch_create_vm_debugfs(struct kvm *kvm);
> +bool kvm_arch_dirty_log_supported(struct kvm *kvm);
>
> #ifndef __KVM_HAVE_ARCH_VM_ALLOC
> /*
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 7a5261eb7eb8..703c1d0c98da 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1467,9 +1467,18 @@ static void kvm_replace_memslot(struct kvm *kvm,
> }
> }
>
> -static int check_memory_region_flags(const struct kvm_userspace_memory_region *mem)
> +bool __weak kvm_arch_dirty_log_supported(struct kvm *kvm)
> {
> - u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
> + return true;
> +}
> +
> +static int check_memory_region_flags(struct kvm *kvm,
> + const struct kvm_userspace_memory_region *mem)
> +{
> + u32 valid_flags = 0;
> +
> + if (kvm_arch_dirty_log_supported(kvm))
> + valid_flags |= KVM_MEM_LOG_DIRTY_PAGES;
>
> #ifdef __KVM_HAVE_READONLY_MEM
> valid_flags |= KVM_MEM_READONLY;
> @@ -1871,7 +1880,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
> int as_id, id;
> int r;
>
> - r = check_memory_region_flags(mem);
> + r = check_memory_region_flags(kvm, mem);
> if (r)
> return r;
>