[PATCH v19 016/130] KVM: x86/mmu: Introduce kvm_mmu_map_tdp_page() for use by TDX

isaku.yamahata
2024-02-26T08:27:47Z

From: Sean Christopherson <sean.j.christopherson@intel.com>

Introduce a helper to directly (pun intended) fault-in a TDP page
without having to go through the full page fault path. This allows
TDX to get the resulting pfn and also allows the RET_PF_* enums to
stay in mmu.c where they belong.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
v19:
- Move up for KVM_MEMORY_MAPPING.
- Add goal_level for the caller to know how many pages are mapped.

v14 -> v15:
- Remove loop in kvm_mmu_map_tdp_page() and return error code based on
RET_FP_xxx value to avoid potential infinite loop. The caller should
loop on -EAGAIN instead now.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/kvm/mmu.h | 3 +++
arch/x86/kvm/mmu/mmu.c | 58 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 61 insertions(+)

diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 60f21bb4c27b..d96c93a25b3b 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -183,6 +183,9 @@ static inline void kvm_mmu_refresh_passthrough_bits(struct kvm_vcpu *vcpu,
__kvm_mmu_refresh_passthrough_bits(vcpu, mmu);
}

+int kvm_mmu_map_tdp_page(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code,
+ u8 max_level, u8 *goal_level);
+
/*
* Check if a given access (described through the I/D, W/R and U/S bits of a
* page fault error code pfec) causes a permission fault with the given PTE
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 61674d6b17aa..ca0c91f14063 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4615,6 +4615,64 @@ int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
return direct_page_fault(vcpu, fault);
}

+int kvm_mmu_map_tdp_page(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code,
+ u8 max_level, u8 *goal_level)
+{
+ int r;
+ struct kvm_page_fault fault = (struct kvm_page_fault) {
+ .addr = gpa,
+ .error_code = error_code,
+ .exec = error_code & PFERR_FETCH_MASK,
+ .write = error_code & PFERR_WRITE_MASK,
+ .present = error_code & PFERR_PRESENT_MASK,
+ .rsvd = error_code & PFERR_RSVD_MASK,
+ .user = error_code & PFERR_USER_MASK,
+ .prefetch = false,
+ .is_tdp = true,
+ .is_private = error_code & PFERR_GUEST_ENC_MASK,
+ .nx_huge_page_workaround_enabled = is_nx_huge_page_enabled(vcpu->kvm),
+ };
+
+ WARN_ON_ONCE(!vcpu->arch.mmu->root_role.direct);
+ fault.slot = kvm_vcpu_gfn_to_memslot(vcpu, fault.gfn);
+
+ r = mmu_topup_memory_caches(vcpu, false);
+ if (r)
+ return r;
+
+ fault.max_level = max_level;
+ fault.req_level = PG_LEVEL_4K;
+ fault.goal_level = PG_LEVEL_4K;
+
+#ifdef CONFIG_X86_64
+ if (tdp_mmu_enabled)
+ r = kvm_tdp_mmu_page_fault(vcpu, &fault);
+ else
+#endif
+ r = direct_page_fault(vcpu, &fault);
+
+ if (is_error_noslot_pfn(fault.pfn) || vcpu->kvm->vm_bugged)
+ return -EFAULT;
+
+ switch (r) {
+ case RET_PF_RETRY:
+ return -EAGAIN;
+
+ case RET_PF_FIXED:
+ case RET_PF_SPURIOUS:
+ if (goal_level)
+ *goal_level = fault.goal_level;
+ return 0;
+
+ case RET_PF_CONTINUE:
+ case RET_PF_EMULATE:
+ case RET_PF_INVALID:
+ default:
+ return -EIO;
+ }
+}
+EXPORT_SYMBOL_GPL(kvm_mmu_map_tdp_page);
+
static void nonpaging_init_context(struct kvm_mmu *context)
{
context->page_fault = nonpaging_page_fault;
--
2.25.1