linux-kernel - [PATCH RFC v7 07/64] KVM: SEV: Handle KVM_HC_MAP_GPA

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Date:   Wed, 14 Dec 2022 13:39:59 -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>,
        Nikunj A Dadhania <nikunj@....com>
Subject: [PATCH RFC v7 07/64] KVM: SEV: Handle KVM_HC_MAP_GPA_RANGE hypercall

From: Nikunj A Dadhania <nikunj@....com>

KVM_HC_MAP_GPA_RANGE hypercall is used by the SEV guest to notify a
change in the page encryption status to the hypervisor.

The hypercall exits to userspace with KVM_EXIT_HYPERCALL exit code,
currently this is used for explicit memory conversion between
shared/private for memfd based private memory.

Signed-off-by: Nikunj A Dadhania <nikunj@....com>
Signed-off-by: Michael Roth <michael.roth@....com>
---
 arch/x86/kvm/x86.c  | 8 ++++++++
 virt/kvm/kvm_main.c | 1 +
 2 files changed, 9 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bb6adb216054..732f9cbbadb5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9649,6 +9649,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 		break;
 	case KVM_HC_MAP_GPA_RANGE: {
 		u64 gpa = a0, npages = a1, attrs = a2;
+		struct kvm_memory_slot *slot;
 
 		ret = -KVM_ENOSYS;
 		if (!(vcpu->kvm->arch.hypercall_exit_enabled & (1 << KVM_HC_MAP_GPA_RANGE)))
@@ -9660,6 +9661,13 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 			break;
 		}
 
+		slot = kvm_vcpu_gfn_to_memslot(vcpu, gpa_to_gfn(gpa));
+		if (!vcpu->kvm->arch.upm_mode ||
+		    !kvm_slot_can_be_private(slot)) {
+			ret = 0;
+			break;
+		}
+
 		vcpu->run->exit_reason        = KVM_EXIT_HYPERCALL;
 		vcpu->run->hypercall.nr       = KVM_HC_MAP_GPA_RANGE;
 		vcpu->run->hypercall.args[0]  = gpa;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d2daa049e94a..73bf0bdedb59 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2646,6 +2646,7 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn
 
 	return NULL;
 }
+EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_memslot);
 
 bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
 {
-- 
2.25.1