From 1bd939d374ec2e994ff47c84e16fa3bc1323a0fd Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Thu, 18 Aug 2022 17:01:13 +0200 Subject: [PATCH 2/2] i386: do kvm_put_msr_feature_control() first thing when vCPU is reset RH-Author: Vitaly Kuznetsov RH-MergeRequest: 216: i386: fix 'system_reset' when the VM is in VMX root operation RH-Bugzilla: 2116743 RH-Acked-by: Emanuele Giuseppe Esposito RH-Acked-by: Miroslav Rezanina RH-Acked-by: Peter Xu RH-Commit: [2/2] f838a57f74487eb394794de00006d5d2b9e84344 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 Message-Id: <20220818150113.479917-3-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini (cherry picked from commit 45ed68a1a3a19754ade954d75a3c9d13ff560e5c) Signed-off-by: Vitaly Kuznetsov --- 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 81d729dc40..a06221d3e5 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -4255,6 +4255,18 @@ 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 = kvm_put_sregs(x86_cpu); if (ret < 0) { @@ -4266,11 +4278,6 @@ 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) { -- 2.31.1