Re: [PATCH 4/5] KVM: SVM: Add correct handling of nested iopm

[Avi Kivity]

On 02/25/2010 07:15 PM, Joerg Roedel wrote:
> This patch adds the correct handling of the nested io
> permission bitmap. Old behavior was to not lookup the port
> in the iopm but only reinject an io intercept to the guest.
>
> Signed-off-by: Joerg Roedel<joerg.roedel@xxxxxxx>
> ---
>   arch/x86/kvm/svm.c |   25 +++++++++++++++++++++++++
>   1 files changed, 25 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index bb75a44..3859e2c 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -78,6 +78,7 @@ struct nested_state {
>
>   	/* gpa pointers to the real vectors */
>   	u64 vmcb_msrpm;
> +	u64 vmcb_iopm;
>
>   	/* A VMEXIT is required but not yet emulated */
>   	bool exit_required;
> @@ -1603,6 +1604,26 @@ static void nested_svm_unmap(struct page *page)
>   	kvm_release_page_dirty(page);
>   }
>
> +static int nested_svm_intercept_ioio(struct vcpu_svm *svm)
> +{
> +	unsigned port;
> +	u8 val, bit;
> +	u64 gpa;
> +
> +	if (!(svm->nested.intercept&  (1ULL<<  INTERCEPT_IOIO_PROT)))
> +		return NESTED_EXIT_HOST;
> +
> +	port = svm->vmcb->control.exit_info_1>>  16;
> +	gpa  = svm->nested.vmcb_iopm + (port / 8);
> +	bit  = port % 8;
> +	val  = 0;
> +
> +	if (kvm_read_guest(svm->vcpu.kvm, gpa,&val, 1))
> +		val&= (1<<  bit);
> +
> +	return val ? NESTED_EXIT_DONE : NESTED_EXIT_HOST;
> +}
> +
>    

A kvm_{test,set,clear}_guest_bit() would be useful, we have several 
users already (not a requirement for this patchset).

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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