FAILED: patch "[PATCH] kvm: vmx: allow host to access guest MSR_IA32_BNDCFGS" failed to apply to 4.12-stable tree

FAILED: patch "[PATCH] kvm: vmx: allow host to access guest MSR_IA32_BNDCFGS" failed to apply to 4.12-stable tree

[gregkh]

The patch below does not apply to the 4.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 691bd4340bef49cf7e5855d06cf24444b5bf2d85 Mon Sep 17 00:00:00 2001
From: Haozhong Zhang <haozhong.zhang@intel.com>
Date: Tue, 4 Jul 2017 10:27:41 +0800
Subject: [PATCH] kvm: vmx: allow host to access guest MSR_IA32_BNDCFGS

It's easier for host applications, such as QEMU, if they can always
access guest MSR_IA32_BNDCFGS in VMCS, even though MPX is disabled in
guest cpuid.

Cc: stable@vger.kernel.org
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index fb0471268a14..b4cfdcfdc1c1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3196,7 +3196,8 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		msr_info->data = vmcs_readl(GUEST_SYSENTER_ESP);
 		break;
 	case MSR_IA32_BNDCFGS:
-		if (!kvm_mpx_supported() || !guest_cpuid_has_mpx(vcpu))
+		if (!kvm_mpx_supported() ||
+		    (!msr_info->host_initiated && !guest_cpuid_has_mpx(vcpu)))
 			return 1;
 		msr_info->data = vmcs_read64(GUEST_BNDCFGS);
 		break;
@@ -3278,7 +3279,8 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		vmcs_writel(GUEST_SYSENTER_ESP, data);
 		break;
 	case MSR_IA32_BNDCFGS:
-		if (!kvm_mpx_supported() || !guest_cpuid_has_mpx(vcpu))
+		if (!kvm_mpx_supported() ||
+		    (!msr_info->host_initiated && !guest_cpuid_has_mpx(vcpu)))
 			return 1;
 		if (is_noncanonical_address(data & PAGE_MASK) ||
 		    (data & MSR_IA32_BNDCFGS_RSVD))

Re: FAILED: patch "[PATCH] kvm: vmx: allow host to access guest MSR_IA32_BNDCFGS" failed to apply to 4.12-stable tree

[haozhong.zhang]

On 07/18/17 17:06 +0200, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 4.12-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> thanks,
> 
> greg k-h

Hi Paolo and Greg,

I think the following patches should be backported as well before
applying mine:

a8b6fda38f80 kvm: vmx: Do not disable intercepts for BNDCFGS
4439af9f911a kvm: x86: Guest BNDCFGS requires guest MPX support
4531662d1abf kvm: vmx: Check value written to IA32_BNDCFGS

Haozhong

> 
> ------------------ original commit in Linus's tree ------------------
> 
> From 691bd4340bef49cf7e5855d06cf24444b5bf2d85 Mon Sep 17 00:00:00 2001
> From: Haozhong Zhang <haozhong.zhang@intel.com>
> Date: Tue, 4 Jul 2017 10:27:41 +0800
> Subject: [PATCH] kvm: vmx: allow host to access guest MSR_IA32_BNDCFGS
> 
> It's easier for host applications, such as QEMU, if they can always
> access guest MSR_IA32_BNDCFGS in VMCS, even though MPX is disabled in
> guest cpuid.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index fb0471268a14..b4cfdcfdc1c1 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3196,7 +3196,8 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>  		msr_info->data = vmcs_readl(GUEST_SYSENTER_ESP);
>  		break;
>  	case MSR_IA32_BNDCFGS:
> -		if (!kvm_mpx_supported() || !guest_cpuid_has_mpx(vcpu))
> +		if (!kvm_mpx_supported() ||
> +		    (!msr_info->host_initiated && !guest_cpuid_has_mpx(vcpu)))
>  			return 1;
>  		msr_info->data = vmcs_read64(GUEST_BNDCFGS);
>  		break;
> @@ -3278,7 +3279,8 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>  		vmcs_writel(GUEST_SYSENTER_ESP, data);
>  		break;
>  	case MSR_IA32_BNDCFGS:
> -		if (!kvm_mpx_supported() || !guest_cpuid_has_mpx(vcpu))
> +		if (!kvm_mpx_supported() ||
> +		    (!msr_info->host_initiated && !guest_cpuid_has_mpx(vcpu)))
>  			return 1;
>  		if (is_noncanonical_address(data & PAGE_MASK) ||
>  		    (data & MSR_IA32_BNDCFGS_RSVD))
> 

Re: FAILED: patch "[PATCH] kvm: vmx: allow host to access guest MSR_IA32_BNDCFGS" failed to apply to 4.12-stable tree

[Greg KH]

On Wed, Jul 19, 2017 at 09:10:58AM +0800, haozhong.zhang@intel.com wrote:
> On 07/18/17 17:06 +0200, gregkh@linuxfoundation.org wrote:
> > 
> > The patch below does not apply to the 4.12-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> > 
> > thanks,
> > 
> > greg k-h
> 
> Hi Paolo and Greg,
> 
> I think the following patches should be backported as well before
> applying mine:
> 
> a8b6fda38f80 kvm: vmx: Do not disable intercepts for BNDCFGS
> 4439af9f911a kvm: x86: Guest BNDCFGS requires guest MPX support
> 4531662d1abf kvm: vmx: Check value written to IA32_BNDCFGS

Thanks, that looks like it worked!

greg k-h

Re: FAILED: patch "[PATCH] kvm: vmx: allow host to access guest MSR_IA32_BNDCFGS" failed to apply to 4.12-stable tree

[Paolo Bonzini]

On 19/07/2017 03:10, haozhong.zhang@intel.com wrote:
> I think the following patches should be backported as well before
> applying mine:
> 
> a8b6fda38f80 kvm: vmx: Do not disable intercepts for BNDCFGS
> 4439af9f911a kvm: x86: Guest BNDCFGS requires guest MPX support
> 4531662d1abf kvm: vmx: Check value written to IA32_BNDCFGS

Ack, all three are good bugfixes for 4.12 (read, safe enough that
Haozhong's patch shouldn't be blocked or backported manually).

Thanks,

Paolo