Re: [PATCH] KVM: nSVM: Fix IOIO bitmap evaluation

[Joerg Roedel <joro@8bytes.org>]

On Mon, Jun 30, 2014 at 10:54:17AM +0200, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> First, kvm_read_guest returns 0 on success. And then we need to take the
> access size into account when testing the bitmap: intercept if any of
> bits corresponding to the access is set.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

Reviewed-by: Joerg Roedel <jroedel@suse.de>
Acked-by: Joerg Roedel <jroedel@suse.de>

I have the slight hope that this fixes the issues with L2 Linux guests
on L1 Windows hypervisors. Have to check that at some point :)

> -	if (kvm_read_guest(svm->vcpu.kvm, gpa, &val, 1))
> -		val &= (1 << bit);
> +	if (kvm_read_guest(svm->vcpu.kvm, gpa, &val, iopm_len))
> +		return NESTED_EXIT_DONE;

Not related to that fix, but as a further improvement we should probably
do a #vmexit(invalid-vmcb) or something if we can't read the iopm.


	Joerg