Re: Patch "KVM, pkeys: do not use PKRU value in vcpu->arch.guest_fpu.state" has been added to the 4.9-stable tree

[Greg KH <gregkh@linuxfoundation.org>]

Oops, no, this didn't build properly, can someone please provide a
working version for 4.9 so that I can apply it?

thanks,

greg k-h


On Sun, Aug 27, 2017 at 09:48:45AM +0200, gregkh@linuxfoundation.org wrote:
> 
> This is a note to let you know that I've just added the patch titled
> 
>     KVM, pkeys: do not use PKRU value in vcpu->arch.guest_fpu.state
> 
> to the 4.9-stable tree which can be found at:
>     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> 
> The filename of the patch is:
>      kvm-pkeys-do-not-use-pkru-value-in-vcpu-arch.guest_fpu.state.patch
> and it can be found in the queue-4.9 subdirectory.
> 
> If you, or anyone else, feels it should not be added to the stable tree,
> please let <stable@vger.kernel.org> know about it.
> 
> 
> >From 38cfd5e3df9c4f88e76b547eee2087ee5c042ae2 Mon Sep 17 00:00:00 2001
> From: Paolo Bonzini <pbonzini@redhat.com>
> Date: Wed, 23 Aug 2017 23:16:29 +0200
> Subject: KVM, pkeys: do not use PKRU value in vcpu->arch.guest_fpu.state
> 
> From: Paolo Bonzini <pbonzini@redhat.com>
> 
> commit 38cfd5e3df9c4f88e76b547eee2087ee5c042ae2 upstream.
> 
> The host pkru is restored right after vcpu exit (commit 1be0e61), so
> KVM_GET_XSAVE will return the host PKRU value instead.  Fix this by
> using the guest PKRU explicitly in fill_xsave and load_xsave.  This
> part is based on a patch by Junkang Fu.
> 
> The host PKRU data may also not match the value in vcpu->arch.guest_fpu.state,
> because it could have been changed by userspace since the last time
> it was saved, so skip loading it in kvm_load_guest_fpu.
> 
> Reported-by: Junkang Fu <junkang.fjk@alibaba-inc.com>
> Cc: Yang Zhang <zy107165@alibaba-inc.com>
> Fixes: 1be0e61c1f255faaeab04a390e00c8b9b9042870
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> ---
>  arch/x86/include/asm/fpu/internal.h |    6 +++---
>  arch/x86/kvm/x86.c                  |   17 ++++++++++++++---
>  2 files changed, 17 insertions(+), 6 deletions(-)
> 
> --- a/arch/x86/include/asm/fpu/internal.h
> +++ b/arch/x86/include/asm/fpu/internal.h
> @@ -445,10 +445,10 @@ static inline int copy_fpregs_to_fpstate
>  	return 0;
>  }
>  
> -static inline void __copy_kernel_to_fpregs(union fpregs_state *fpstate)
> +static inline void __copy_kernel_to_fpregs(union fpregs_state *fpstate, u64 mask)
>  {
>  	if (use_xsave()) {
> -		copy_kernel_to_xregs(&fpstate->xsave, -1);
> +		copy_kernel_to_xregs(&fpstate->xsave, mask);
>  	} else {
>  		if (use_fxsr())
>  			copy_kernel_to_fxregs(&fpstate->fxsave);
> @@ -472,7 +472,7 @@ static inline void copy_kernel_to_fpregs
>  			: : [addr] "m" (fpstate));
>  	}
>  
> -	__copy_kernel_to_fpregs(fpstate);
> +	__copy_kernel_to_fpregs(fpstate, -1);
>  }
>  
>  extern int copy_fpstate_to_sigframe(void __user *buf, void __user *fp, int size);
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3179,7 +3179,12 @@ static void fill_xsave(u8 *dest, struct
>  			u32 size, offset, ecx, edx;
>  			cpuid_count(XSTATE_CPUID, index,
>  				    &size, &offset, &ecx, &edx);
> -			memcpy(dest + offset, src, size);
> +			if (feature == XFEATURE_MASK_PKRU)
> +				memcpy(dest + offset, &vcpu->arch.pkru,
> +				       sizeof(vcpu->arch.pkru));
> +			else
> +				memcpy(dest + offset, src, size);
> +
>  		}
>  
>  		valid -= feature;
> @@ -3217,7 +3222,11 @@ static void load_xsave(struct kvm_vcpu *
>  			u32 size, offset, ecx, edx;
>  			cpuid_count(XSTATE_CPUID, index,
>  				    &size, &offset, &ecx, &edx);
> -			memcpy(dest, src + offset, size);
> +			if (feature == XFEATURE_MASK_PKRU)
> +				memcpy(&vcpu->arch.pkru, src + offset,
> +				       sizeof(vcpu->arch.pkru));
> +			else
> +				memcpy(dest, src + offset, size);
>  		}
>  
>  		valid -= feature;
> @@ -7453,7 +7462,9 @@ void kvm_load_guest_fpu(struct kvm_vcpu
>  	 */
>  	vcpu->guest_fpu_loaded = 1;
>  	__kernel_fpu_begin();
> -	__copy_kernel_to_fpregs(&vcpu->arch.guest_fpu.state);
> +	/* PKRU is separately restored in kvm_x86_ops->run.  */
> +	__copy_kernel_to_fpregs(&vcpu->arch.guest_fpu.state,
> +				~XFEATURE_MASK_PKRU);
>  	trace_kvm_fpu(1);
>  }
>  
> 
> 
> Patches currently in stable-queue which might be from pbonzini@redhat.com are
> 
> queue-4.9/kvm-x86-block-guest-protection-keys-unless-the-host-has-them-enabled.patch
> queue-4.9/kvm-pkeys-do-not-use-pkru-value-in-vcpu-arch.guest_fpu.state.patch