[patch 4/5] KVM: VMX: EPT misconfiguration handler

Marcelo Tosatti
2009-06-09T21:34:54Z

[-- Attachment #1: vmx-misconfig-handler --]
[-- Type: text/plain, Size: 3355 bytes --]

Handler for EPT misconfiguration which checks for valid state
in the shadow pagetables, printing the spte on each level.

The separate WARN_ONs are useful for kerneloops.org.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm/arch/x86/kvm/vmx.c
===================================================================
--- kvm.orig/arch/x86/kvm/vmx.c
+++ kvm/arch/x86/kvm/vmx.c
@@ -3173,6 +3173,100 @@ static int handle_ept_violation(struct k
return kvm_mmu_page_fault(vcpu, gpa & PAGE_MASK, 0);
}

+static u64 ept_rsvd_mask(u64 *sptep, int level)
+{
+ int i;
+ u64 mask = 0;
+
+ for (i = 51; i > boot_cpu_data.x86_phys_bits; i--)
+ mask |= (1ULL << i);
+
+ if (level > 2)
+ /* bits 7:3 reserved */
+ mask |= 0xf8;
+ else if (level == 2) {
+ if (*sptep & (1ULL << 7))
+ /* 2MB ref, bits 20:12 reserved */
+ mask |= 0x1ff000;
+ else
+ /* bits 6:3 reserved */
+ mask |= 0x78;
+ }
+
+ return mask;
+}
+
+struct ept_inspect_spte {
+ int print;
+ struct mmu_shadow_walk walk;
+};
+
+static int ept_misconfig_inspect_spte(struct kvm_vcpu *vcpu, u64 *sptep,
+ int level,
+ struct mmu_shadow_walk *walk)
+{
+ struct ept_inspect_spte *iept = container_of(walk,
+ struct ept_inspect_spte, walk);
+
+ if (iept->print)
+ printk(KERN_ERR "%s: sptep %p spte 0x%llx level %d\n",
+ __func__, sptep, *sptep, level);
+
+ /* 010b (write-only) */
+ WARN_ON((*sptep & 0x7) == 0x2);
+
+ /* 110b (write/execute) */
+ WARN_ON((*sptep & 0x7) == 0x6);
+
+ /* 100b (execute-only) and value not supported by logical processor */
+ if (!cpu_has_vmx_ept_execute_only())
+ WARN_ON((*sptep & 0x7) == 0x4);
+
+ /* not 000b */
+ if ((*sptep & 0x7)) {
+ u64 rsvd_bits = *sptep & ept_rsvd_mask(sptep, level);
+
+ if (rsvd_bits != 0) {
+ printk(KERN_ERR "%s: rsvd_bits = 0x%llx\n",
+ __func__, rsvd_bits);
+ WARN_ON(1);
+ }
+
+ if (level == 1 || (level == 2 && (*sptep & (1ULL << 7)))) {
+ u64 ept_mem_type = (*sptep & 0x38) >> 3;
+
+ if (ept_mem_type == 2 || ept_mem_type == 3 ||
+ ept_mem_type == 7) {
+ printk(KERN_ERR "%s: ept_mem_type=0x%llx\n",
+ __func__, ept_mem_type);
+ WARN_ON(1);
+ }
+ }
+ }
+
+ return 0;
+}
+
+static int handle_ept_misconfig(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+ gpa_t gpa;
+ struct ept_inspect_spte iept = { .print = 1,
+ .walk.fn =
+ ept_misconfig_inspect_spte };
+
+ gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
+
+ printk(KERN_ERR "EPT: Misconfiguration.\n");
+ printk(KERN_ERR "EPT: GPA: 0x%llx\n", gpa);
+
+ kvm_mmu_shadow_walk(vcpu, gpa, &iept.walk);
+
+ kvm_run->exit_reason = KVM_EXIT_UNKNOWN;
+ kvm_run->hw.hardware_exit_reason = EXIT_REASON_EPT_MISCONFIG;
+
+ return 0;
+}
+
static int handle_nmi_window(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
u32 cpu_based_vm_exec_control;
@@ -3243,8 +3337,9 @@ static int (*kvm_vmx_exit_handlers[])(st
[EXIT_REASON_APIC_ACCESS] = handle_apic_access,
[EXIT_REASON_WBINVD] = handle_wbinvd,
[EXIT_REASON_TASK_SWITCH] = handle_task_switch,
- [EXIT_REASON_EPT_VIOLATION] = handle_ept_violation,
[EXIT_REASON_MCE_DURING_VMENTRY] = handle_machine_check,
+ [EXIT_REASON_EPT_VIOLATION] = handle_ept_violation,
+ [EXIT_REASON_EPT_MISCONFIG] = handle_ept_misconfig,
};

static const int kvm_vmx_max_exit_handlers =