From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Date: Wed, May 8, 2019 at 12:55 PM To: Aaron Lewis Cc: Peter Shier, Paolo Bonzini, <rkrcmar@xxxxxxxxxx>, Jim Mattson, Marc Orr, <kvm@xxxxxxxxxxxxxxx> > Aaron Lewis <aaronlewis@xxxxxxxxxx> writes: > > > From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> > > Date: Fri, May 3, 2019 at 3:25 AM > > To: Aaron Lewis > > Cc: Peter Shier, <pbonzini@xxxxxxxxxx>, <rkrcmar@xxxxxxxxxx>, > > <jmattson@xxxxxxxxxx>, <marcorr@xxxxxxxxxx>, <kvm@xxxxxxxxxxxxxxx> > > > >> Aaron Lewis <aaronlewis@xxxxxxxxxx> writes: > >> > >> > Move call to nested_enable_evmcs until after free_nested() is complete. > >> > > >> > Signed-off-by: Aaron Lewis <aaronlewis@xxxxxxxxxx> > >> > Reviewed-by: Marc Orr <marcorr@xxxxxxxxxx> > >> > Reviewed-by: Peter Shier <pshier@xxxxxxxxxx> > >> > --- > >> > arch/x86/kvm/vmx/nested.c | 6 +++--- > >> > 1 file changed, 3 insertions(+), 3 deletions(-) > >> > > >> > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c > >> > index 081dea6e211a..3b39c60951ac 100644 > >> > --- a/arch/x86/kvm/vmx/nested.c > >> > +++ b/arch/x86/kvm/vmx/nested.c > >> > @@ -5373,9 +5373,6 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu, > >> > if (kvm_state->format != 0) > >> > return -EINVAL; > >> > > >> > - if (kvm_state->flags & KVM_STATE_NESTED_EVMCS) > >> > - nested_enable_evmcs(vcpu, NULL); > >> > - > >> > if (!nested_vmx_allowed(vcpu)) > >> > return kvm_state->vmx.vmxon_pa == -1ull ? 0 : -EINVAL; > >> > > >> > @@ -5417,6 +5414,9 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu, > >> > if (kvm_state->vmx.vmxon_pa == -1ull) > >> > return 0; > >> > > >> > + if (kvm_state->flags & KVM_STATE_NESTED_EVMCS) > >> > + nested_enable_evmcs(vcpu, NULL); > >> > + > >> > vmx->nested.vmxon_ptr = kvm_state->vmx.vmxon_pa; > >> > ret = enter_vmx_operation(vcpu); > >> > if (ret) > >> > >> nested_enable_evmcs() doesn't do much, actually, in case it was > >> previously enabled it doesn't do anything and in case it wasn't ordering > >> with free_nested() (where you're aiming at nested_release_evmcs() I > >> would guess) shouldn't matter. So could you please elaborate (better in > >> the commit message) why do we need this re-ordered? My guess is that > >> you'd like to perform checks for e.g. 'vmx.vmxon_pa == -1ull' before > >> we actually start doing any changes but let's clarify that. > >> > >> Thanks! > >> > >> -- > >> Vitaly > > > > There are two reasons for doing this: > > 1. We don't want to set new state if we are going to leave nesting and > > exit the function (ie: vmx.vmxon_pa = -1), like you pointed out. > > 2. To be more future proof, we don't want to set new state before > > tearing down state. This could cause conflicts down the road. > > > > I can add this to the commit message if there are no objections to > > these points. > > Sounds good to me, please do. Thanks! > > -- > Vitaly Here is the updated patch: Move call to nested_enable_evmcs until after free_nested() is complete. There are two reasons for doing this: 1. We don't want to set new state if we are going to leave nesting and exit the function (ie: vmx.vmxon_pa = -1). 2. To be more future proof, we don't want to set new state before tearing down state. This could cause conflicts down the road. Signed-off-by: Aaron Lewis <aaronlewis@xxxxxxxxxx> Reviewed-by: Marc Orr <marcorr@xxxxxxxxxx> Reviewed-by: Peter Shier <pshier@xxxxxxxxxx> --- arch/x86/kvm/vmx/nested.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index fe5814df5149..6ecc301df874 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -5373,9 +5373,6 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu, if (kvm_state->format != 0) return -EINVAL; - if (kvm_state->flags & KVM_STATE_NESTED_EVMCS) - nested_enable_evmcs(vcpu, NULL); - if (!nested_vmx_allowed(vcpu)) return kvm_state->vmx.vmxon_pa == -1ull ? 0 : -EINVAL; @@ -5417,6 +5414,9 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu, if (kvm_state->vmx.vmxon_pa == -1ull) return 0; + if (kvm_state->flags & KVM_STATE_NESTED_EVMCS) + nested_enable_evmcs(vcpu, NULL); + vmx->nested.vmxon_ptr = kvm_state->vmx.vmxon_pa; ret = enter_vmx_operation(vcpu); if (ret)
