linux-kernel - [PATCH 6/7] KVM: x86: Implement kvm_arch_vcpu_map

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Message-ID: <20240417153450.3608097-7-pbonzini@redhat.com>
Date: Wed, 17 Apr 2024 11:34:49 -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 6/7] KVM: x86: Implement kvm_arch_vcpu_map_memory()

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

Wire KVM_MAP_MEMORY ioctl to kvm_mmu_map_tdp_page() to populate guest
memory.  When KVM_CREATE_VCPU creates vCPU, it initializes the x86
KVM MMU part by kvm_mmu_create() and kvm_init_mmu().  vCPU is ready to
invoke the KVM page fault handler.

Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
Message-ID: <7138a3bc00ea8d3cbe0e59df15f8c22027005b59.1712785629.git.isaku.yamahata@...el.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/Kconfig |  1 +
 arch/x86/kvm/x86.c   | 43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 7632fe6e4db9..e58360d368ec 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -44,6 +44,7 @@ config KVM
 	select KVM_VFIO
 	select HAVE_KVM_PM_NOTIFIER if PM
 	select KVM_GENERIC_HARDWARE_ENABLING
+	select KVM_GENERIC_MAP_MEMORY
 	help
 	  Support hosting fully virtualized guest machines using hardware
 	  virtualization extensions.  You will need a fairly recent
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 83b8260443a3..f84c75c2a47f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4715,6 +4715,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_MEMORY_FAULT_INFO:
 		r = 1;
 		break;
+	case KVM_CAP_MAP_MEMORY:
+		r = tdp_enabled;
+		break;
 	case KVM_CAP_EXIT_HYPERCALL:
 		r = KVM_EXIT_HYPERCALL_VALID_MASK;
 		break;
@@ -5867,6 +5870,46 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
 	}
 }
 
+int kvm_arch_vcpu_map_memory(struct kvm_vcpu *vcpu,
+			     struct kvm_map_memory *mapping)
+{
+	u64 mapped, end, error_code = 0;
+	u8 level = PG_LEVEL_4K;
+	int r;
+
+	/*
+	 * Shadow paging uses GVA for kvm page fault.  The first implementation
+	 * supports GPA only to avoid confusion.
+	 */
+	if (!tdp_enabled)
+		return -EOPNOTSUPP;
+
+	/*
+	 * reload is efficient when called repeatedly, so we can do it on
+	 * every iteration.
+	 */
+	kvm_mmu_reload(vcpu);
+
+	if (kvm_arch_has_private_mem(vcpu->kvm) &&
+	    kvm_mem_is_private(vcpu->kvm, gpa_to_gfn(mapping->base_address)))
+		error_code |= PFERR_PRIVATE_ACCESS;
+
+	r = kvm_tdp_map_page(vcpu, mapping->base_address, error_code, &level);
+	if (r)
+		return r;
+
+	/*
+	 * level can be more than the alignment of mapping->base_address if
+	 * the mapping can use a huge page.
+	 */
+	end = (mapping->base_address & KVM_HPAGE_MASK(level)) +
+		KVM_HPAGE_SIZE(level);
+	mapped = min(mapping->size, end - mapping->base_address);
+	mapping->size -= mapped;
+	mapping->base_address += mapped;
+	return r;
+}
+
 long kvm_arch_vcpu_ioctl(struct file *filp,
 			 unsigned int ioctl, unsigned long arg)
 {
-- 
2.43.0