linux-kernel - [PATCH 2/5] KVM: VMX: Add guest physical address check in EPT violation and misconfig

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Date:   Thu, 27 Feb 2020 19:23:03 +0200
From:   Mohammed Gamal <mgamal@...hat.com>
To:     kvm@...r.kernel.org, pbonzini@...hat.com
Cc:     sean.j.christopherson@...el.com, vkuznets@...hat.com,
        wanpengli@...cent.com, jmattson@...gle.com, joro@...tes.org,
        linux-kernel@...r.kernel.org, Mohammed Gamal <mgamal@...hat.com>
Subject: [PATCH 2/5] KVM: VMX: Add guest physical address check in EPT violation and misconfig

Check guest physical address against it's maximum physical memory. If
the guest's physical address exceeds the maximum (i.e. has reserved bits
set), inject a guest page fault with PFERR_RSVD_MASK.

Signed-off-by: Mohammed Gamal <mgamal@...hat.com>
---
 arch/x86/kvm/vmx/vmx.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 63aaf44edd1f..477d196aa235 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5162,6 +5162,12 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
 	gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
 	trace_kvm_page_fault(gpa, exit_qualification);
 
+	/* Check if guest gpa doesn't exceed physical memory limits */
+	if (gpa >= (1ull << cpuid_maxphyaddr(vcpu))) {
+		kvm_inject_rsvd_bits_pf(vcpu, gpa);
+		return 1;
+	}
+
 	/* Is it a read fault? */
 	error_code = (exit_qualification & EPT_VIOLATION_ACC_READ)
 		     ? PFERR_USER_MASK : 0;
@@ -5193,6 +5199,13 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu)
 	 * nGPA here instead of the required GPA.
 	 */
 	gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
+
+	/* Check if guest gpa doesn't exceed physical memory limits */
+	if (gpa >= (1ull << cpuid_maxphyaddr(vcpu))) {
+		kvm_inject_rsvd_bits_pf(vcpu, gpa);
+		return 1;
+	}
+
 	if (!is_guest_mode(vcpu) &&
 	    !kvm_io_bus_write(vcpu, KVM_FAST_MMIO_BUS, gpa, 0, NULL)) {
 		trace_kvm_fast_mmio(gpa);
-- 
2.21.1