Re: [PATCH v4 07/10] x86/mm: add vmtrace_buf resource type

From: "Roger Pau Monné" <roger.pau@citrix.com>
To: "Michał Leszczyński" <michal.leszczynski@cert.pl>
Cc: Julien Grall <julien@xen.org>,
	Stefano Stabellini <sstabellini@kernel.org>,
	tamas.lengyel@intel.com, Wei Liu <wl@xen.org>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>,
	George Dunlap <george.dunlap@citrix.com>,
	luwei.kang@intel.com, Jan Beulich <jbeulich@suse.com>,
	xen-devel@lists.xenproject.org
Subject: Re: [PATCH v4 07/10] x86/mm: add vmtrace_buf resource type
Date: Wed, 1 Jul 2020 12:52:16 +0200	[thread overview]
Message-ID: <20200701105216.GT735@Air-de-Roger> (raw)
In-Reply-To: <2446caa5be5eca36f0b5ca47d2edcbd6f7792484.1593519420.git.michal.leszczynski@cert.pl>

On Tue, Jun 30, 2020 at 02:33:50PM +0200, Michał Leszczyński wrote:
> From: Michal Leszczynski <michal.leszczynski@cert.pl>
> 
> Allow to map processor trace buffer using
> acquire_resource().
> 
> Signed-off-by: Michal Leszczynski <michal.leszczynski@cert.pl>
> ---
>  xen/arch/x86/mm.c           | 25 +++++++++++++++++++++++++
>  xen/include/public/memory.h |  1 +
>  2 files changed, 26 insertions(+)
> 
> diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
> index e376fc7e8f..bb781bd90c 100644
> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -4624,6 +4624,31 @@ int arch_acquire_resource(struct domain *d, unsigned int type,
>          }
>          break;
>      }
> +
> +    case XENMEM_resource_vmtrace_buf:
> +    {
> +        mfn_t mfn;
> +        unsigned int i;
> +        struct vcpu *v = domain_vcpu(d, id);

Missing blank newline between variable definitions and code.

> +        rc = -EINVAL;
> +
> +        if ( !v )
> +            break;
> +
> +        if ( !v->arch.vmtrace.pt_buf )
> +            break;
> +
> +        mfn = page_to_mfn(v->arch.vmtrace.pt_buf);
> +
> +        if ( frame + nr_frames > (v->domain->vmtrace_pt_size >> PAGE_SHIFT) )
> +            break;

You can place all the checks done above in a single if.

Thanks, Roger.