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[PATCH v1 2/2] i386: do kvm_put_msr_feature_control() first thing when v
From: |
Vitaly Kuznetsov |
Subject: |
[PATCH v1 2/2] i386: do kvm_put_msr_feature_control() first thing when vCPU is reset |
Date: |
Thu, 18 Aug 2022 17:01:13 +0200 |
kvm_put_sregs2() fails to reset 'locked' CR4/CR0 bits upon vCPU reset when
it is in VMX root operation. Do kvm_put_msr_feature_control() before
kvm_put_sregs2() to (possibly) kick vCPU out of VMX root operation. It also
seems logical to do kvm_put_msr_feature_control() before
kvm_put_nested_state() and not after it, especially when 'real' nested
state is set.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
target/i386/kvm/kvm.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 4f8dacc1d4b5..a1fd1f53791d 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -4529,6 +4529,18 @@ int kvm_arch_put_registers(CPUState *cpu, int level)
assert(cpu_is_stopped(cpu) || qemu_cpu_is_self(cpu));
+ /*
+ * Put MSR_IA32_FEATURE_CONTROL first, this ensures the VM gets out of VMX
+ * root operation upon vCPU reset. kvm_put_msr_feature_control() should
also
+ * preceed kvm_put_nested_state() when 'real' nested state is set.
+ */
+ if (level >= KVM_PUT_RESET_STATE) {
+ ret = kvm_put_msr_feature_control(x86_cpu);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
/* must be before kvm_put_nested_state so that EFER.SVME is set */
ret = has_sregs2 ? kvm_put_sregs2(x86_cpu) : kvm_put_sregs(x86_cpu);
if (ret < 0) {
@@ -4540,11 +4552,6 @@ int kvm_arch_put_registers(CPUState *cpu, int level)
if (ret < 0) {
return ret;
}
-
- ret = kvm_put_msr_feature_control(x86_cpu);
- if (ret < 0) {
- return ret;
- }
}
if (level == KVM_PUT_FULL_STATE) {
--
2.37.1