Re: [PATCH] Fixup sida bouncing

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On 14/11/2019 17.21, Janosch Frank wrote:
> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> ---
>  arch/s390/kvm/kvm-s390.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 0fa7c6d9ed0e..9820fde04887 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -4432,13 +4432,21 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
>  	if (mop->size > MEM_OP_MAX_SIZE)
>  		return -E2BIG;
>  
> -	/* Protected guests move instruction data over the satellite
> +	/*
> +	 * Protected guests move instruction data over the satellite
>  	 * block which has its own size limit
>  	 */
>  	if (kvm_s390_pv_is_protected(vcpu->kvm) &&
> -	    mop->size > ((vcpu->arch.sie_block->sidad & 0x0f) + 1) * PAGE_SIZE)
> +	    mop->size > ((vcpu->arch.sie_block->sidad & 0xff) + 1) * PAGE_SIZE)
>  		return -E2BIG;
>  
> +	/* We can currently only offset into the one SIDA page. */
> +	if (kvm_s390_pv_is_protected(vcpu->kvm)) {
> +		mop->gaddr &= ~PAGE_MASK;
> +		if (mop->gaddr + mop->size > PAGE_SIZE)
> +			return -EINVAL;
> +	}
> +
>  	if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
>  		tmpbuf = vmalloc(mop->size);
>  		if (!tmpbuf)
> @@ -4451,6 +4459,7 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
>  	case KVM_S390_MEMOP_LOGICAL_READ:
>  		if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) {
>  			if (kvm_s390_pv_is_protected(vcpu->kvm)) {
> +				/* We can always copy into the SIDA */
>  				r = 0;
>  				break;
>  			}
> @@ -4461,8 +4470,7 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
>  		if (kvm_s390_pv_is_protected(vcpu->kvm)) {
>  			r = 0;
>  			if (copy_to_user(uaddr, (void *)vcpu->arch.sie_block->sidad +
> -					 (mop->gaddr & ~PAGE_MASK),
> -					 mop->size))
> +					 mop->gaddr, mop->size))
>  				r = -EFAULT;
>  			break;
>  		}
> @@ -4485,8 +4493,7 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
>  		if (kvm_s390_pv_is_protected(vcpu->kvm)) {
>  			r = 0;
>  			if (copy_from_user((void *)vcpu->arch.sie_block->sidad +
> -					   (mop->gaddr & ~PAGE_MASK), uaddr,
> -					   mop->size))
> +					   mop->gaddr, uaddr, mop->size))
>  				r = -EFAULT;
>  			break;
>  		}
> 

That looks better, indeed.

Still, is there a way you could also verify that gaddr references the
right page that is mirrored in the sidad?

 Thomas





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