linux-kernel - [PATCH RFC v7 04/64] KVM: x86: Add 'fault_is

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Date:   Wed, 14 Dec 2022 13:39:56 -0600
From:   Michael Roth <michael.roth@....com>
To:     <kvm@...r.kernel.org>
CC:     <linux-coco@...ts.linux.dev>, <linux-mm@...ck.org>,
        <linux-crypto@...r.kernel.org>, <x86@...nel.org>,
        <linux-kernel@...r.kernel.org>, <tglx@...utronix.de>,
        <mingo@...hat.com>, <jroedel@...e.de>, <thomas.lendacky@....com>,
        <hpa@...or.com>, <ardb@...nel.org>, <pbonzini@...hat.com>,
        <seanjc@...gle.com>, <vkuznets@...hat.com>,
        <wanpengli@...cent.com>, <jmattson@...gle.com>, <luto@...nel.org>,
        <dave.hansen@...ux.intel.com>, <slp@...hat.com>,
        <pgonda@...gle.com>, <peterz@...radead.org>,
        <srinivas.pandruvada@...ux.intel.com>, <rientjes@...gle.com>,
        <dovmurik@...ux.ibm.com>, <tobin@....com>, <bp@...en8.de>,
        <vbabka@...e.cz>, <kirill@...temov.name>, <ak@...ux.intel.com>,
        <tony.luck@...el.com>, <marcorr@...gle.com>,
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        <alpergun@...gle.com>, <dgilbert@...hat.com>, <jarkko@...nel.org>,
        <ashish.kalra@....com>, <harald@...fian.com>
Subject: [PATCH RFC v7 04/64] KVM: x86: Add 'fault_is_private' x86 op

This callback is used by the KVM MMU to check whether a #NPF was
or a private GPA or not.

Signed-off-by: Michael Roth <michael.roth@....com>
---
 arch/x86/include/asm/kvm-x86-ops.h |  1 +
 arch/x86/include/asm/kvm_host.h    |  1 +
 arch/x86/kvm/mmu/mmu.c             |  3 +--
 arch/x86/kvm/mmu/mmu_internal.h    | 40 +++++++++++++++++++++++++++---
 4 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index f530a550c092..efae987cdce0 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -132,6 +132,7 @@ KVM_X86_OP(complete_emulated_msr)
 KVM_X86_OP(vcpu_deliver_sipi_vector)
 KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons);
 KVM_X86_OP_OPTIONAL_RET0(private_mem_enabled);
+KVM_X86_OP_OPTIONAL_RET0(fault_is_private);
 
 #undef KVM_X86_OP
 #undef KVM_X86_OP_OPTIONAL
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9317abffbf68..92539708f062 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1636,6 +1636,7 @@ struct kvm_x86_ops {
 	void (*load_mmu_pgd)(struct kvm_vcpu *vcpu, hpa_t root_hpa,
 			     int root_level);
 	int (*private_mem_enabled)(struct kvm *kvm);
+	int (*fault_is_private)(struct kvm *kvm, gpa_t gpa, u64 error_code, bool *private_fault);
 
 	bool (*has_wbinvd_exit)(void);
 
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index b3ffc61c668c..61a7c221b966 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5646,8 +5646,7 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err
 	}
 
 	if (r == RET_PF_INVALID) {
-		r = kvm_mmu_do_page_fault(vcpu, cr2_or_gpa,
-					  lower_32_bits(error_code), false);
+		r = kvm_mmu_do_page_fault(vcpu, cr2_or_gpa, error_code, false);
 		if (KVM_BUG_ON(r == RET_PF_INVALID, vcpu->kvm))
 			return -EIO;
 	}
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index e2f508db0b6e..04ea8da86510 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -230,6 +230,38 @@ struct kvm_page_fault {
 
 int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
 
+static bool kvm_mmu_fault_is_private(struct kvm *kvm, gpa_t gpa, u64 err)
+{
+	struct kvm_memory_slot *slot;
+	bool private_fault = false;
+	gfn_t gfn = gpa_to_gfn(gpa);
+
+	slot = gfn_to_memslot(kvm, gfn);
+	if (!slot) {
+		pr_debug("%s: no slot, GFN: 0x%llx\n", __func__, gfn);
+		goto out;
+	}
+
+	if (!kvm_slot_can_be_private(slot)) {
+		pr_debug("%s: slot is not private, GFN: 0x%llx\n", __func__, gfn);
+		goto out;
+	}
+
+	if (static_call(kvm_x86_fault_is_private)(kvm, gpa, err, &private_fault) == 1)
+		goto out;
+
+	/*
+	 * Handling below is for UPM self-tests and guests that use
+	 * slot->shared_bitmap for encrypted access tracking.
+	 */
+	if (IS_ENABLED(CONFIG_HAVE_KVM_PRIVATE_MEM_TESTING))
+		private_fault = kvm_mem_is_private(kvm, gpa >> PAGE_SHIFT);
+
+out:
+	pr_debug("%s: GFN: 0x%llx, private: %d\n", __func__, gfn, private_fault);
+	return private_fault;
+}
+
 /*
  * Return values of handle_mmio_page_fault(), mmu.page_fault(), fast_page_fault(),
  * and of course kvm_mmu_do_page_fault().
@@ -261,13 +293,13 @@ enum {
 };
 
 static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
-					u32 err, bool prefetch)
+					u64 err, bool prefetch)
 {
 	bool is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault);
 
 	struct kvm_page_fault fault = {
 		.addr = cr2_or_gpa,
-		.error_code = err,
+		.error_code = lower_32_bits(err),
 		.exec = err & PFERR_FETCH_MASK,
 		.write = err & PFERR_WRITE_MASK,
 		.present = err & PFERR_PRESENT_MASK,
@@ -281,8 +313,8 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 		.max_level = KVM_MAX_HUGEPAGE_LEVEL,
 		.req_level = PG_LEVEL_4K,
 		.goal_level = PG_LEVEL_4K,
-		.is_private = IS_ENABLED(CONFIG_HAVE_KVM_PRIVATE_MEM_TESTING) && is_tdp &&
-				kvm_mem_is_private(vcpu->kvm, cr2_or_gpa >> PAGE_SHIFT),
+		.is_private = is_tdp && kvm_mmu_fault_is_private(vcpu->kvm,
+								 cr2_or_gpa, err),
 	};
 	int r;
 
-- 
2.25.1