On Wed, Sep 21, 2022 at 10:35:44AM -0700,
David Matlack <dmatlack@xxxxxxxxxx> wrote:
> Split out the page fault handling for the TDP MMU to a separate
> function. This creates some duplicate code, but makes the TDP MMU fault
> handler simpler to read by eliminating branches and will enable future
> cleanups by allowing the TDP MMU and non-TDP MMU fault paths to diverge.
>
> Only compile in the TDP MMU fault handler for 64-bit builds since
> kvm_tdp_mmu_map() does not exist in 32-bit builds.
>
> No functional change intended.
>
> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
> ---
> arch/x86/kvm/mmu/mmu.c | 62 ++++++++++++++++++++++++++++++++----------
> 1 file changed, 48 insertions(+), 14 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index dc203973de83..b36f351138f7 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -4238,7 +4238,6 @@ static bool is_page_fault_stale(struct kvm_vcpu *vcpu,
>
> static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
> {
> - bool is_tdp_mmu_fault = is_tdp_mmu(vcpu->arch.mmu);
> int r;
>
> if (page_fault_handle_page_track(vcpu, fault))
> @@ -4257,11 +4256,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
> return r;
>
> r = RET_PF_RETRY;
> -
> - if (is_tdp_mmu_fault)
> - read_lock(&vcpu->kvm->mmu_lock);
> - else
> - write_lock(&vcpu->kvm->mmu_lock);
> + write_lock(&vcpu->kvm->mmu_lock);
>
> if (is_page_fault_stale(vcpu, fault))
> goto out_unlock;
> @@ -4270,16 +4265,10 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
> if (r)
> goto out_unlock;
>
> - if (is_tdp_mmu_fault)
> - r = kvm_tdp_mmu_map(vcpu, fault);
> - else
> - r = __direct_map(vcpu, fault);
> + r = __direct_map(vcpu, fault);
>
> out_unlock:
> - if (is_tdp_mmu_fault)
> - read_unlock(&vcpu->kvm->mmu_lock);
> - else
> - write_unlock(&vcpu->kvm->mmu_lock);
> + write_unlock(&vcpu->kvm->mmu_lock);
> kvm_release_pfn_clean(fault->pfn);
> return r;
> }
> @@ -4327,6 +4316,46 @@ int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code,
> }
> EXPORT_SYMBOL_GPL(kvm_handle_page_fault);
>
> +#ifdef CONFIG_X86_64
> +static int kvm_tdp_mmu_page_fault(struct kvm_vcpu *vcpu,
> + struct kvm_page_fault *fault)
> +{
> + int r;
> +
> + if (page_fault_handle_page_track(vcpu, fault))
> + return RET_PF_EMULATE;
> +
> + r = fast_page_fault(vcpu, fault);
> + if (r != RET_PF_INVALID)
> + return r;
> +
> + r = mmu_topup_memory_caches(vcpu, false);
> + if (r)
> + return r;
> +
> + r = kvm_faultin_pfn(vcpu, fault, ACC_ALL);
> + if (r != RET_PF_CONTINUE)
> + return r;
> +
> + r = RET_PF_RETRY;
> + read_lock(&vcpu->kvm->mmu_lock);
> +
> + if (is_page_fault_stale(vcpu, fault))
> + goto out_unlock;
> +
> + r = make_mmu_pages_available(vcpu);
> + if (r)
> + goto out_unlock;
> +
> + r = kvm_tdp_mmu_map(vcpu, fault);
> +
> +out_unlock:
> + read_unlock(&vcpu->kvm->mmu_lock);
> + kvm_release_pfn_clean(fault->pfn);
> + return r;
> +}
> +#endif
> +
> int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
> {
> /*
> @@ -4351,6 +4380,11 @@ int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
> }
> }
>
> +#ifdef CONFIG_X86_64
> + if (tdp_mmu_enabled)
> + return kvm_tdp_mmu_page_fault(vcpu, fault);
> +#endif
> +
> return direct_page_fault(vcpu, fault);
> }
>
> --
> 2.37.3.998.g577e59143f-goog
>
Reviewed-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
--
Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
