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

From: Borislav Petkov <bp@alien8.de>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: kvm@vger.kernel.org,
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Subject: Re: [PATCH v2 8/9] KVM: x86: add force_intercept_exceptions_mask
Date: Tue, 27 Apr 2021 13:38:40 +0200	[thread overview]
Message-ID: <YIf3wM1+enU1U/gn@zn.tnic> (raw)
In-Reply-To: <20210401135451.1004564-9-mlevitsk@redhat.com>

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.

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