From: Jan Beulich <jbeulich@suse.com>
To: Tamas K Lengyel <tamas.lengyel@intel.com>
Cc: "George Dunlap" <george.dunlap@eu.citrix.com>,
xen-devel@lists.xenproject.org,
"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
"Andrew Cooper" <andrew.cooper3@citrix.com>
Subject: Re: [Xen-devel] [PATCH v8 1/5] x86/p2m: Allow p2m_get_page_from_gfn to return shared entries
Date: Tue, 11 Feb 2020 10:16:14 +0100 [thread overview]
Message-ID: <f620590a-147b-eeb8-707c-72cac10753bd@suse.com> (raw)
In-Reply-To: <cf992d6e4dd09acc48afb42d43be4a900baee189.1581362050.git.tamas.lengyel@intel.com>
On 10.02.2020 20:21, Tamas K Lengyel wrote:
> The owner domain of shared pages is dom_cow, use that for get_page
> otherwise the function fails to return the correct page under some
> situations. The check if dom_cow should be used was only performed in
> a subset of use-cases. Fixing the error and simplifying the existing check
> since we can't have any shared entries with dom_cow being NULL.
>
> Signed-off-by: Tamas K Lengyel <tamas.lengyel@intel.com>
I find it quite disappointing that the blank lines requested to be
added ...
> --- a/xen/arch/x86/mm/p2m.c
> +++ b/xen/arch/x86/mm/p2m.c
> @@ -574,11 +574,12 @@ struct page_info *p2m_get_page_from_gfn(
> if ( fdom == NULL )
> page = NULL;
> }
> - else if ( !get_page(page, p2m->domain) &&
> - /* Page could be shared */
> - (!dom_cow || !p2m_is_shared(*t) ||
> - !get_page(page, dom_cow)) )
> - page = NULL;
> + else
> + {
> + struct domain *d = !p2m_is_shared(*t) ? p2m->domain : dom_cow;
> + if ( !get_page(page, d) )
.. above here and ...
> @@ -594,8 +595,9 @@ struct page_info *p2m_get_page_from_gfn(
> mfn = get_gfn_type_access(p2m, gfn_x(gfn), t, a, q, NULL);
> if ( p2m_is_ram(*t) && mfn_valid(mfn) )
> {
> + struct domain *d = !p2m_is_shared(*t) ? p2m->domain : dom_cow;
> page = mfn_to_page(mfn);
... above here still haven't appeared. No matter that it's easy to
do so while committing, when you send a new version you should
really address such remarks yourself, I think.
Jan
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next prev parent reply other threads:[~2020-02-11 9:16 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 19:21 [Xen-devel] [PATCH v8 0/5] VM forking Tamas K Lengyel
2020-02-10 19:21 ` [Xen-devel] [PATCH v8 1/5] x86/p2m: Allow p2m_get_page_from_gfn to return shared entries Tamas K Lengyel
2020-02-11 9:16 ` Jan Beulich [this message]
2020-02-11 10:29 ` Tamas K Lengyel
2020-02-11 11:04 ` Jan Beulich
2020-02-11 13:34 ` Tamas K Lengyel
2020-02-21 13:48 ` Andrew Cooper
2020-02-21 14:21 ` Tamas K Lengyel
2020-02-10 19:21 ` [Xen-devel] [PATCH v8 2/5] xen/x86: Make hap_get_allocation accessible Tamas K Lengyel
2020-02-10 19:21 ` [Xen-devel] [PATCH v8 3/5] xen/mem_sharing: VM forking Tamas K Lengyel
2020-02-21 13:43 ` Andrew Cooper
2020-02-21 14:02 ` Andrew Cooper
2020-02-21 14:22 ` Tamas K Lengyel
2020-02-21 14:42 ` Andrew Cooper
2020-02-21 17:07 ` Tamas K Lengyel
2020-02-21 17:47 ` Andrew Cooper
2020-02-21 17:56 ` Tamas K Lengyel
2020-02-21 18:08 ` Tamas K Lengyel
2020-02-10 19:21 ` [Xen-devel] [PATCH v8 4/5] x86/mem_sharing: reset a fork Tamas K Lengyel
2020-02-10 19:21 ` [Xen-devel] [PATCH v8 5/5] xen/tools: VM forking toolstack side Tamas K Lengyel
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