linux-kernel - [PATCH 5/7] KVM: x86/mmu: Introduce kvm_tdp_map

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Message-ID: <20240417153450.3608097-6-pbonzini@redhat.com>
Date: Wed, 17 Apr 2024 11:34:48 -0400
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Cc: isaku.yamahata@...el.com,
	xiaoyao.li@...el.com,
	binbin.wu@...ux.intel.com,
	seanjc@...gle.com,
	rick.p.edgecombe@...el.com
Subject: [PATCH 5/7] KVM: x86/mmu: Introduce kvm_tdp_map_page() to populate guest memory

From: Isaku Yamahata <isaku.yamahata@...el.com>

Introduce a helper function to call the KVM fault handler.  It allows a new
ioctl to invoke the KVM fault handler to populate without seeing RET_PF_*
enums or other KVM MMU internal definitions because RET_PF_* are internal
to x86 KVM MMU.  The implementation is restricted to two-dimensional paging
for simplicity.  The shadow paging uses GVA for faulting instead of L1 GPA.
It makes the API difficult to use.

Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
Message-ID: <9b866a0ae7147f96571c439e75429a03dcb659b6.1712785629.git.isaku.yamahata@...el.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/mmu.h     |  3 +++
 arch/x86/kvm/mmu/mmu.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index e8b620a85627..51ff4f67e115 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_tdp_map_page(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code,
+		     u8 *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 7fbcfc97edcc..fb2149d16f8d 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4646,6 +4646,38 @@ int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 	return direct_page_fault(vcpu, fault);
 }
 
+int kvm_tdp_map_page(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code,
+		     u8 *level)
+{
+	int r;
+
+	/* Restrict to TDP page fault. */
+	if (vcpu->arch.mmu->page_fault != kvm_tdp_page_fault)
+		return -EOPNOTSUPP;
+
+	r = __kvm_mmu_do_page_fault(vcpu, gpa, error_code, true, NULL, level);
+	if (r < 0)
+		return r;
+
+	switch (r) {
+	case RET_PF_RETRY:
+		return -EAGAIN;
+
+	case RET_PF_FIXED:
+	case RET_PF_SPURIOUS:
+		return 0;
+
+	case RET_PF_EMULATE:
+		return -EINVAL;
+
+	case RET_PF_CONTINUE:
+	case RET_PF_INVALID:
+	default:
+		WARN_ON_ONCE(r);
+		return -EIO;
+	}
+}
+
 static void nonpaging_init_context(struct kvm_mmu *context)
 {
 	context->page_fault = nonpaging_page_fault;
-- 
2.43.0