Re: [PATCH v2 8/9] KVM: x86: add force_intercept_exceptions_mask

Borislav Petkov
2021-04-27T11:38:48Z

On Thu, Apr 01, 2021 at 04:54:50PM +0300, Maxim Levitsky wrote:
> This parameter will be used by VMX and SVM code to force
> interception of a set of exceptions, given by a bitmask
> for guest debug and/or kvm debug.
>
> This option is not intended for production.
>
> This is based on an idea first shown here:
> https://patchwork.kernel.org/project/kvm/patch/20160301192822.GD22677@pd.tnic/
>
> CC: Borislav Petkov <bp@suse.de>
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
> arch/x86/kvm/x86.c | 3 +++
> arch/x86/kvm/x86.h | 2 ++
> 2 files changed, 5 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 3627ce8fe5bb..1a51031d64d8 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -176,6 +176,9 @@ module_param(force_emulation_prefix, bool, S_IRUGO);
> int __read_mostly pi_inject_timer = -1;
> module_param(pi_inject_timer, bint, S_IRUGO | S_IWUSR);
>
> +uint force_intercept_exceptions_mask;
> +module_param(force_intercept_exceptions_mask, uint, S_IRUGO | S_IWUSR);
> +EXPORT_SYMBOL_GPL(force_intercept_exceptions_mask);

That's nice.

I could use some text explaning the usage though, i.e. that thing takes
a bitfield of exception vectors, so that I don't have to look at the
code each time. :-)

Thx.

--
Regards/Gruss,
Boris.