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authorXiao Guangrong <guangrong.xiao@linux.intel.com>2016-03-22 11:51:18 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2016-03-22 18:21:06 +0300
commit1be0e61c1f255faaeab04a390e00c8b9b9042870 (patch)
treefc4a8f06af57bff2529a55dafc7918289827683e /arch
parent9e90199c25aec31b4509213881511948f6c763c8 (diff)
downloadlinux-1be0e61c1f255faaeab04a390e00c8b9b9042870.tar.xz
KVM, pkeys: save/restore PKRU when guest/host switches
Currently XSAVE state of host is not restored after VM-exit and PKRU is managed by XSAVE so the PKRU from guest is still controlling the memory access even if the CPU is running the code of host. This is not safe as KVM needs to access the memory of userspace (e,g QEMU) to do some emulation. So we save/restore PKRU when guest/host switches. Signed-off-by: Huaitong Han <huaitong.han@intel.com> Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/vmx.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1b8a41f64d35..87664775b51e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -598,6 +598,10 @@ struct vcpu_vmx {
struct page *pml_pg;
u64 current_tsc_ratio;
+
+ bool guest_pkru_valid;
+ u32 guest_pkru;
+ u32 host_pkru;
};
enum segment_cache_field {
@@ -2107,6 +2111,7 @@ static void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
} while (cmpxchg(&pi_desc->control, old.control,
new.control) != old.control);
}
+
/*
* Switches to specified vcpu, until a matching vcpu_put(), but assumes
* vcpu mutex is already taken.
@@ -2167,6 +2172,7 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
}
vmx_vcpu_pi_load(vcpu, cpu);
+ vmx->host_pkru = read_pkru();
}
static void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu)
@@ -8639,6 +8645,9 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
vmx_set_interrupt_shadow(vcpu, 0);
+ if (vmx->guest_pkru_valid)
+ __write_pkru(vmx->guest_pkru);
+
atomic_switch_perf_msrs(vmx);
debugctlmsr = get_debugctlmsr();
@@ -8779,6 +8788,20 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
vmx->exit_reason = vmcs_read32(VM_EXIT_REASON);
/*
+ * eager fpu is enabled if PKEY is supported and CR4 is switched
+ * back on host, so it is safe to read guest PKRU from current
+ * XSAVE.
+ */
+ if (boot_cpu_has(X86_FEATURE_OSPKE)) {
+ vmx->guest_pkru = __read_pkru();
+ if (vmx->guest_pkru != vmx->host_pkru) {
+ vmx->guest_pkru_valid = true;
+ __write_pkru(vmx->host_pkru);
+ } else
+ vmx->guest_pkru_valid = false;
+ }
+
+ /*
* the KVM_REQ_EVENT optimization bit is only on for one entry, and if
* we did not inject a still-pending event to L1 now because of
* nested_run_pending, we need to re-enable this bit.