Re: [PATCH v4 05/10] common/domain: allocate vmtrace_pt_buffer

From: Julien Grall <julien@xen.org>
To: "Michał Leszczyński" <michal.leszczynski@cert.pl>,
	xen-devel@lists.xenproject.org
Cc: "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>,
	"Jan Beulich" <jbeulich@suse.com>,
	luwei.kang@intel.com, "Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH v4 05/10] common/domain: allocate vmtrace_pt_buffer
Date: Wed, 1 Jul 2020 16:35:56 +0100	[thread overview]
Message-ID: <3c710ce8-c561-fd73-3be8-a92456588db9@xen.org> (raw)
In-Reply-To: <0e02c97054da6e367f740ab8d2574e2d255553c8.1593519420.git.michal.leszczynski@cert.pl>

Hi,

On 30/06/2020 13:33, Michał Leszczyński wrote:
> +static int vmtrace_alloc_buffers(struct vcpu *v)
> +{
> +    struct page_info *pg;
> +    uint64_t size = v->domain->vmtrace_pt_size;
> +
> +    if ( size < PAGE_SIZE || size > GB(4) || (size & (size - 1)) )
> +    {
> +        /*
> +         * We don't accept trace buffer size smaller than single page
> +         * and the upper bound is defined as 4GB in the specification.

This is common code, so what specification are you talking about?

I am guessing this is an Intel one, but I don't think Intel should 
dictate the common code implementation.

> +         * The buffer size must be also a power of 2.
> +         */
> +        return -EINVAL;
> +    }
> +
> +    pg = alloc_domheap_pages(v->domain, get_order_from_bytes(size),
> +                             MEMF_no_refcount);
> +
> +    if ( !pg )
> +        return -ENOMEM;
> +
> +    v->arch.vmtrace.pt_buf = pg;

v->arch.vmtrace.pt_buf is not defined on Arm. Please make sure common 
code build on all arch.

Cheers,

-- 
Julien Grall