2022-02-18 13:18:29

by Hao Peng

Subject: [PATCH] kvm/vmx: Make setup/unsetup under the same conditions

Make sure nested_vmx_hardware_setup/unsetup are called in pairs under
the same conditions.

Signed-off-by: Peng Hao <[email protected]>
---
arch/x86/kvm/vmx/vmx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 0ffcfe54eea5..5392def71093 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7852,7 +7852,7 @@ static __init int hardware_setup(void)
vmx_set_cpu_caps();

r = alloc_kvm_area();
- if (r)
+ if (r && nested)
nested_vmx_hardware_unsetup();

kvm_set_posted_intr_wakeup_handler(pi_wakeup_handler);
--
2.27.0

2022-02-18 21:50:38

by Sean Christopherson

Subject: Re: [PATCH] kvm/vmx: Make setup/unsetup under the same conditions

"KVM: VMX" for the scope, or maybe even "KVM: nVMX:" despite this not touching
vmx/nested.c. Either way (but not "kvm/vmx:").

On Fri, Feb 18, 2022, Peng Hao wrote:
> Make sure nested_vmx_hardware_setup/unsetup are called in pairs under
> the same conditions.

Probably worth adding a sentence to clarify that the existing code isn't buggy
only because free_page() plays nice with getting passed '0' and vmx_bitmap is
initialized to zero. Something like:

Make sure nested_vmx_hardware_setup/unsetup() are called in pairs under
the same conditions. Calling nested_vmx_hardware_unsetup() when nested
is false "works" right now because it only calls free_page() on zero-
initialized pointers, but it's possible that more code will be added to
nested_vmx_hardware_unsetup() in the future.

Reviewed-by: Sean Christopherson <[email protected]>


>
> Signed-off-by: Peng Hao <[email protected]>
> ---
> arch/x86/kvm/vmx/vmx.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 0ffcfe54eea5..5392def71093 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7852,7 +7852,7 @@ static __init int hardware_setup(void)
> vmx_set_cpu_caps();
>
> r = alloc_kvm_area();
> - if (r)
> + if (r && nested)
> nested_vmx_hardware_unsetup();
>
> kvm_set_posted_intr_wakeup_handler(pi_wakeup_handler);
> --
> 2.27.0
>