[PATCH 21/45] KVM: Take memory protections into account for __kvm_vcpu_map

[Paolo Bonzini <pbonzini@redhat.com>]

Take into account memory attributes when establishing a long term map
through kvm_vcpu_map()/kvm_vcpu_map_readonly().

Unlike the gfn-to-pfn cache, changes to the attributes will not be
propagated, so that it will be possible to place a nested VMCS, VMCB,
or APIC access page on a non-readable/writable page.  This will be
fixed separately by using a gfn-to-pfn cache for nested virtualization
data structures, in the meanwhile apply a stopgap fix.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://patch.msgid.link/20260918135030.171564-18-pbonzini@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 virt/kvm/kvm_main.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index de54f52f2158..c7b8d1bcf893 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3302,6 +3302,11 @@ int __kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map,
 	if (WARN_ON_ONCE(map->hva))
 		kvm_vcpu_unmap(vcpu, map);
 
+	if (!kvm_mem_attributes_may_read_gfn(vcpu->kvm, gfn))
+		return -EFAULT;
+	if (writable && !kvm_mem_attributes_may_write_gfn(vcpu->kvm, gfn))
+		return -EFAULT;
+
 	map->pinned_page = NULL;
 	map->page = NULL;
 	map->hva = NULL;
-- 
2.52.0