linux-kernel - [PATCH RFC v1 3/9] KVM: x86/mmu: Add hook to pin PFNs on demand in MMU

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Message-ID: <20220308043857.13652-4-nikunj@amd.com>
Date:   Tue, 8 Mar 2022 10:08:51 +0530
From:   Nikunj A Dadhania <nikunj@....com>
To:     Paolo Bonzini <pbonzini@...hat.com>
CC:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Brijesh Singh <brijesh.singh@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Peter Gonda <pgonda@...gle.com>,
        Bharata B Rao <bharata@....com>,
        "Maciej S . Szmigiero" <mail@...iej.szmigiero.name>,
        Mingwei Zhang <mizhang@...gle.com>,
        "David Hildenbrand" <david@...hat.com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Nikunj A Dadhania <nikunj@....com>
Subject: [PATCH RFC v1 3/9] KVM: x86/mmu: Add hook to pin PFNs on demand in MMU

Use vendor code via kvm_x86_ops hooks for pinning.

Signed-off-by: Nikunj A Dadhania <nikunj@....com>
---
 arch/x86/include/asm/kvm-x86-ops.h |  1 +
 arch/x86/include/asm/kvm_host.h    |  3 +++
 arch/x86/kvm/mmu/mmu.c             | 15 +++++++++++++++
 3 files changed, 19 insertions(+)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index d39e0de06be2..8efb43d92eef 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -88,6 +88,7 @@ KVM_X86_OP(set_tss_addr)
 KVM_X86_OP(set_identity_map_addr)
 KVM_X86_OP(get_mt_mask)
 KVM_X86_OP(load_mmu_pgd)
+KVM_X86_OP(pin_pfn)
 KVM_X86_OP_NULL(has_wbinvd_exit)
 KVM_X86_OP(get_l2_tsc_offset)
 KVM_X86_OP(get_l2_tsc_multiplier)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index ec9830d2aabf..df11f1fb76de 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1418,6 +1418,9 @@ struct kvm_x86_ops {
 
 	void (*load_mmu_pgd)(struct kvm_vcpu *vcpu, hpa_t root_hpa,
 			     int root_level);
+	bool (*pin_pfn)(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
+			kvm_pfn_t pfn, hva_t hva, bool write,
+			enum pg_level level);
 
 	bool (*has_wbinvd_exit)(void);
 
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index db1feecd6fed..b94e5e71653e 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4001,6 +4001,16 @@ static bool is_page_fault_stale(struct kvm_vcpu *vcpu,
 	       mmu_notifier_retry_hva(vcpu->kvm, mmu_seq, fault->hva);
 }
 
+static bool kvm_pin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
+{
+	if (is_error_noslot_pfn(fault->pfn) || kvm_is_reserved_pfn(fault->pfn) ||
+	    !kvm_x86_ops.pin_pfn)
+		return true;
+
+	return kvm_x86_ops.pin_pfn(vcpu, fault->slot, fault->pfn, fault->hva,
+				   fault->write, fault->goal_level);
+}
+
 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);
@@ -4035,6 +4045,9 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
 
 	kvm_mmu_hugepage_adjust(vcpu, fault);
 
+	if (memslot_is_encrypted(fault->slot) && !kvm_pin_pfn(vcpu, fault))
+		goto out_release;
+
 	if (is_tdp_mmu_fault)
 		read_lock(&vcpu->kvm->mmu_lock);
 	else
@@ -4057,6 +4070,8 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
 		read_unlock(&vcpu->kvm->mmu_lock);
 	else
 		write_unlock(&vcpu->kvm->mmu_lock);
+
+out_release:
 	kvm_release_pfn_clean(fault->pfn);
 	return r;
 }
-- 
2.32.0