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KVM: nVMX: Improve nested msr switch checking

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This patch improve checks required by Intel Software Developer Manual.
 - SMM MSRs are not allowed.
 - microcode MSRs are not allowed.
 - check x2apic MSRs only when LAPIC is in x2apic mode.
 - MSR switch areas must be aligned to 16 bytes.
 - address of first and last byte in MSR switch areas should not set any bits
   beyond the processor's physical-address width.

Also it adds warning messages on failures during MSR switch. These messages
are useful for people who debug their VMMs in nVMX.

Signed-off-by: Eugene Korenevsky <ekorenevsky@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Eugene Korenevsky 2014-12-11 08:53:27 +03:00 • committed by Paolo Bonzini
commit e9ac033e6b
2 changed files with 117 additions and 14 deletions
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3
arch/x86/include/uapi/asm/msr-index.h
View file

@ -356,6 +356,9 @@
#define MSR_IA32_UCODE_WRITE 0x00000079
#define MSR_IA32_UCODE_REV 0x0000008b
#define MSR_IA32_SMM_MONITOR_CTL 0x0000009b
#define MSR_IA32_SMBASE 0x0000009e
#define MSR_IA32_PERF_STATUS 0x00000198
#define MSR_IA32_PERF_CTL 0x00000199
#define MSR_AMD_PSTATE_DEF_BASE 0xc0010064

126
arch/x86/kvm/vmx.c
View file

@ -8293,18 +8293,80 @@ static void vmx_start_preemption_timer(struct kvm_vcpu *vcpu)
ns_to_ktime(preemption_timeout), HRTIMER_MODE_REL);
}
static inline int nested_vmx_msr_check_common(struct vmx_msr_entry *e)
static int nested_vmx_check_msr_switch(struct kvm_vcpu *vcpu,
unsigned long count_field,
unsigned long addr_field,
int maxphyaddr)
{
if (e->index >> 8 == 0x8 || e->reserved != 0)
u64 count, addr;
if (vmcs12_read_any(vcpu, count_field, &count) ||
vmcs12_read_any(vcpu, addr_field, &addr)) {
WARN_ON(1);
return -EINVAL;
}
if (count == 0)
return 0;
if (!IS_ALIGNED(addr, 16) || addr >> maxphyaddr ||
(addr + count * sizeof(struct vmx_msr_entry) - 1) >> maxphyaddr) {
pr_warn_ratelimited(
"nVMX: invalid MSR switch (0x%lx, %d, %llu, 0x%08llx)",
addr_field, maxphyaddr, count, addr);
return -EINVAL;
}
return 0;
}
static int nested_vmx_check_msr_switch_controls(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12)
{
int maxphyaddr;
if (vmcs12->vm_exit_msr_load_count == 0 &&
vmcs12->vm_exit_msr_store_count == 0 &&
vmcs12->vm_entry_msr_load_count == 0)
return 0; /* Fast path */
maxphyaddr = cpuid_maxphyaddr(vcpu);
if (nested_vmx_check_msr_switch(vcpu, VM_EXIT_MSR_LOAD_COUNT,
VM_EXIT_MSR_LOAD_ADDR, maxphyaddr) ||
nested_vmx_check_msr_switch(vcpu, VM_EXIT_MSR_STORE_COUNT,
VM_EXIT_MSR_STORE_ADDR, maxphyaddr) ||
nested_vmx_check_msr_switch(vcpu, VM_ENTRY_MSR_LOAD_COUNT,
VM_ENTRY_MSR_LOAD_ADDR, maxphyaddr))
return -EINVAL;
return 0;
}
static inline int nested_vmx_load_msr_check(struct vmx_msr_entry *e)
static int nested_vmx_msr_check_common(struct kvm_vcpu *vcpu,
struct vmx_msr_entry *e)
{
/* x2APIC MSR accesses are not allowed */
if (apic_x2apic_mode(vcpu->arch.apic) && e->index >> 8 == 0x8)
return -EINVAL;
if (e->index == MSR_IA32_UCODE_WRITE || /* SDM Table 35-2 */
e->index == MSR_IA32_UCODE_REV)
return -EINVAL;
if (e->reserved != 0)
return -EINVAL;
return 0;
}
static int nested_vmx_load_msr_check(struct kvm_vcpu *vcpu,
struct vmx_msr_entry *e)
{
if (e->index == MSR_FS_BASE ||
e->index == MSR_GS_BASE ||
nested_vmx_msr_check_common(e))
e->index == MSR_IA32_SMM_MONITOR_CTL || /* SMM is not supported */
nested_vmx_msr_check_common(vcpu, e))
return -EINVAL;
return 0;
}
static int nested_vmx_store_msr_check(struct kvm_vcpu *vcpu,
struct vmx_msr_entry *e)
{
if (e->index == MSR_IA32_SMBASE || /* SMM is not supported */
nested_vmx_msr_check_common(vcpu, e))
return -EINVAL;
return 0;
}
@ -8321,14 +8383,28 @@ static u32 nested_vmx_load_msr(struct kvm_vcpu *vcpu, u64 gpa, u32 count)
msr.host_initiated = false;
for (i = 0; i < count; i++) {
kvm_read_guest(vcpu->kvm, gpa + i * sizeof(e), &e, sizeof(e));
if (nested_vmx_load_msr_check(&e))
if (kvm_read_guest(vcpu->kvm, gpa + i * sizeof(e),
&e, sizeof(e))) {
pr_warn_ratelimited(
"%s cannot read MSR entry (%u, 0x%08llx)\n",
__func__, i, gpa + i * sizeof(e));
goto fail;
}
if (nested_vmx_load_msr_check(vcpu, &e)) {
pr_warn_ratelimited(
"%s check failed (%u, 0x%x, 0x%x)\n",
__func__, i, e.index, e.reserved);
goto fail;
}
msr.index = e.index;
msr.data = e.value;
if (kvm_set_msr(vcpu, &msr))
if (kvm_set_msr(vcpu, &msr)) {
pr_warn_ratelimited(
"%s cannot write MSR (%u, 0x%x, 0x%llx)\n",
__func__, i, e.index, e.value);
goto fail;
}
}
return 0;
fail:
return i + 1;
@ -8340,16 +8416,35 @@ static int nested_vmx_store_msr(struct kvm_vcpu *vcpu, u64 gpa, u32 count)
struct vmx_msr_entry e;
for (i = 0; i < count; i++) {
kvm_read_guest(vcpu->kvm, gpa + i * sizeof(e),
&e, 2 * sizeof(u32));
if (nested_vmx_msr_check_common(&e))
if (kvm_read_guest(vcpu->kvm,
gpa + i * sizeof(e),
&e, 2 * sizeof(u32))) {
pr_warn_ratelimited(
"%s cannot read MSR entry (%u, 0x%08llx)\n",
__func__, i, gpa + i * sizeof(e));
return -EINVAL;
if (kvm_get_msr(vcpu, e.index, &e.value))
}
if (nested_vmx_store_msr_check(vcpu, &e)) {
pr_warn_ratelimited(
"%s check failed (%u, 0x%x, 0x%x)\n",
__func__, i, e.index, e.reserved);
return -EINVAL;
kvm_write_guest(vcpu->kvm,
}
if (kvm_get_msr(vcpu, e.index, &e.value)) {
pr_warn_ratelimited(
"%s cannot read MSR (%u, 0x%x)\n",
__func__, i, e.index);
return -EINVAL;
}
if (kvm_write_guest(vcpu->kvm,
gpa + i * sizeof(e) +
offsetof(struct vmx_msr_entry, value),
&e.value, sizeof(e.value));
&e.value, sizeof(e.value))) {
pr_warn_ratelimited(
"%s cannot write MSR (%u, 0x%x, 0x%llx)\n",
__func__, i, e.index, e.value);
return -EINVAL;
}
}
return 0;
}
@ -8698,6 +8793,11 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
return 1;
}
if (nested_vmx_check_msr_switch_controls(vcpu, vmcs12)) {
nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);
return 1;
}
if (!vmx_control_verify(vmcs12->cpu_based_vm_exec_control,
nested_vmx_true_procbased_ctls_low,
nested_vmx_procbased_ctls_high) ||