Re: [PATCH v5 1/6] x86: allow IRQ to be disabled for resource access

From: "Jan Beulich" <JBeulich@suse.com>
To: Chao Peng <chao.p.peng@linux.intel.com>
Cc: wei.liu2@citrix.com, Ian.Campbell@citrix.com,
	stefano.stabellini@eu.citrix.com, Ian.Jackson@eu.citrix.com,
	xen-devel@lists.xen.org, will.auld@intel.com, keir@xen.org
Subject: Re: [PATCH v5 1/6] x86: allow IRQ to be disabled for resource access
Date: Thu, 22 Jan 2015 11:18:43 +0000	[thread overview]
Message-ID: <54C0EAA302000078000580E7@mail.emea.novell.com> (raw)
In-Reply-To: <1421839164-26037-2-git-send-email-chao.p.peng@linux.intel.com>

>>> On 21.01.15 at 12:19, <chao.p.peng@linux.intel.com> wrote:
> --- a/xen/arch/x86/platform_hypercall.c
> +++ b/xen/arch/x86/platform_hypercall.c
> @@ -90,7 +90,9 @@ static void check_resource_access(struct xen_resource_access *ra)
>          int ret = 0;
>          xenpf_resource_entry_t *entry = ra->entries + i;
>  
> -        if ( entry->rsvd )
> +        /* DISABLE_IRQ flag should never be set for the last entry */
> +        if ( entry->flags & XEN_RESOURCE_ENTRY_FLAGS_DISABLE_IRQ &&

This needs checking that all the other 31 bits are clear as well as
parenthesizing.

> @@ -124,11 +126,19 @@ static void resource_access(void *info)
>  {
>      struct xen_resource_access *ra = info;
>      unsigned int i;
> +    unsigned long irqflags = 0;
> +    bool_t irq_disabled = 0;

I don't think you need two variables for this - this is x86-only code
and EFLAGS bit 1 is always set.

Jan