On Mon, 16 Feb 2015 13:16:41 +0100
Thomas Huth <thuth@xxxxxxxxxxxxxxxxxx> wrote:
> On s390, we've got to make sure to hold the IPTE lock while accessing
> logical memory. So let's add an ioctl for reading and writing logical
> memory to provide this feature for userspace, too.
>
> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxxxxxxxxxx>
> ---
> Documentation/virtual/kvm/api.txt | 45 +++++++++++++++++++++++
> arch/s390/kvm/gaccess.c | 22 +++++++++++
> arch/s390/kvm/gaccess.h | 2 +
> arch/s390/kvm/kvm-s390.c | 70 +++++++++++++++++++++++++++++++++++++
> include/uapi/linux/kvm.h | 20 ++++++++++
> 5 files changed, 159 insertions(+), 0 deletions(-)
Looks good, except for one minor thing:
> +static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
> + struct kvm_s390_mem_op *mop)
> +{
> + void __user *uaddr = (void __user *)mop->buf;
> + void *tmpbuf = NULL;
> + int r, srcu_idx;
> + const u64 supported_flags = KVM_S390_MEMOP_F_INJECT_EXCEPTION
> + | KVM_S390_MEMOP_F_CHECK_ONLY;
> +
> + if (mop->flags & ~supported_flags)
> + return -EINVAL;
> +
> + if (mop->size > 16 * PAGE_SIZE)
> + return -E2BIG;
Do you want to document this limit? Or make it discoverable by having
the capability check return the number of pages?
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