2021-04-09 02:26:15

by Haiwei Li

Subject: [PATCH v2] KVM: vmx: add mismatched size assertions in vmcs_check32()

From: Haiwei Li <[email protected]>

Add compile-time assertions in vmcs_check32() to disallow accesses to
64-bit and 64-bit high fields via vmcs_{read,write}32(). Upper level KVM
code should never do partial accesses to VMCS fields. KVM handles the
split accesses automatically in vmcs_{read,write}64() when running as a
32-bit kernel.

Reviewed-and-tested-by: Sean Christopherson <[email protected]>
Signed-off-by: Haiwei Li <[email protected]>
---
v1 -> v2:
* Improve the changelog

arch/x86/kvm/vmx/vmx_ops.h | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx_ops.h b/arch/x86/kvm/vmx/vmx_ops.h
index 692b0c3..164b64f 100644
--- a/arch/x86/kvm/vmx/vmx_ops.h
+++ b/arch/x86/kvm/vmx/vmx_ops.h
@@ -37,6 +37,10 @@ static __always_inline void vmcs_check32(unsigned long field)
{
BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6000) == 0,
"32-bit accessor invalid for 16-bit field");
+ BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6001) == 0x2000,
+ "32-bit accessor invalid for 64-bit field");
+ BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6001) == 0x2001,
+ "32-bit accessor invalid for 64-bit high field");
BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6000) == 0x6000,
"32-bit accessor invalid for natural width field");
}
--
1.8.3.1

2021-04-17 13:19:06

by Paolo Bonzini

Subject: Re: [PATCH v2] KVM: vmx: add mismatched size assertions in vmcs_check32()

On 09/04/21 04:24, [email protected] wrote:
> From: Haiwei Li <[email protected]>
>
> Add compile-time assertions in vmcs_check32() to disallow accesses to
> 64-bit and 64-bit high fields via vmcs_{read,write}32(). Upper level KVM
> code should never do partial accesses to VMCS fields. KVM handles the
> split accesses automatically in vmcs_{read,write}64() when running as a
> 32-bit kernel.
>
> Reviewed-and-tested-by: Sean Christopherson <[email protected]>
> Signed-off-by: Haiwei Li <[email protected]>
> ---
> v1 -> v2:
> * Improve the changelog
>
> arch/x86/kvm/vmx/vmx_ops.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx/vmx_ops.h b/arch/x86/kvm/vmx/vmx_ops.h
> index 692b0c3..164b64f 100644
> --- a/arch/x86/kvm/vmx/vmx_ops.h
> +++ b/arch/x86/kvm/vmx/vmx_ops.h
> @@ -37,6 +37,10 @@ static __always_inline void vmcs_check32(unsigned long field)
> {
> BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6000) == 0,
> "32-bit accessor invalid for 16-bit field");
> + BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6001) == 0x2000,
> + "32-bit accessor invalid for 64-bit field");
> + BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6001) == 0x2001,
> + "32-bit accessor invalid for 64-bit high field");
> BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6000) == 0x6000,
> "32-bit accessor invalid for natural width field");
> }
>

Queued, thanks.

paolo