Re: [Xen-devel] [PATCH] domain_create: honour global grant/maptrack frame limits...

From: "Durrant, Paul" <pdurrant@amazon.com>
To: "Durrant, Paul" <pdurrant@amazon.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [Xen-devel] [PATCH] domain_create: honour global grant/maptrack frame limits...
Date: Wed, 13 Nov 2019 13:51:48 +0000	[thread overview]
Message-ID: <57a6e3f262da4f258fba7142ebb4d615@EX13D32EUC003.ant.amazon.com> (raw)
In-Reply-To: <20191113134729.1121-1-pdurrant@amazon.com>

Sorry, the Cc list got dropped... I'll re-send.

  Paul

> -----Original Message-----
> From: Paul Durrant <pdurrant@amazon.com>
> Sent: 13 November 2019 13:47
> To: xen-devel@lists.xenproject.org
> Cc: Durrant, Paul <pdurrant@amazon.com>
> Subject: [PATCH] domain_create: honour global grant/maptrack frame
> limits...
> 
> ...when their values are larger than the per-domain configured limits.
> 
> Signed-off-by: Paul Durrant <pdurrant@amazon.com>
> ---
> After mining through commits it is still unclear to me exactly when Xen
> stopped honouring the global values, but I really think this commit should
> be back-ported to stable trees as it was a behavioural change that can
> cause domUs to fail in non-obvious ways.
> ---
>  xen/common/domain.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/common/domain.c b/xen/common/domain.c
> index 611116c7fc..aad6d55b82 100644
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -335,6 +335,7 @@ struct domain *domain_create(domid_t domid,
>      enum { INIT_watchdog = 1u<<1,
>             INIT_evtchn = 1u<<3, INIT_gnttab = 1u<<4, INIT_arch = 1u<<5 };
>      int err, init_status = 0;
> +    unsigned int max_grant_frames, max_maptrack_frames;
> 
>      if ( config && (err = sanitise_domain_config(config)) )
>          return ERR_PTR(err);
> @@ -456,8 +457,17 @@ struct domain *domain_create(domid_t domid,
>              goto fail;
>          init_status |= INIT_evtchn;
> 
> -        if ( (err = grant_table_init(d, config->max_grant_frames,
> -                                     config->max_maptrack_frames)) != 0 )
> +        /*
> +         * Make sure that the configured values don't reduce any
> +         * global command line override.
> +         */
> +        max_grant_frames = max(config->max_grant_frames,
> +                               opt_max_grant_frames);
> +        max_maptrack_frames = max(config->max_maptrack_frames,
> +                                  opt_max_maptrack_frames);
> +
> +        if ( (err = grant_table_init(d, max_grant_frames,
> +                                     max_maptrack_frames)) != 0 )
>              goto fail;
>          init_status |= INIT_gnttab;
> 
> --
> 2.17.1

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