From: "Ahmed S. Darwish" <darwish.07@gmail.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Rusty Russel <rusty@rustcorp.com.au>,
Suresh Siddha <suresh.b.siddha@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
lguest@ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH] lguest: Accept guest _PAGE_PWT page table entries
Date: Thu, 7 Feb 2008 02:51:20 +0200 [thread overview]
Message-ID: <20080207005120.GA5751@ubuntu> (raw)
In-Reply-To: <20080206235923.GA19843@elte.hu>
On Thu, Feb 07, 2008 at 12:59:23AM +0100, Ingo Molnar wrote:
>
> * Ahmed S. Darwish <darwish.07@gmail.com> wrote:
>
> > Hi all,
> >
> > Beginning from commit 4138cc3418f5, ioremap_nocache() sets the _PAGE_PWT
> > flag.
> >
> > Lguest doesn't accept a guest pte with a _PWT flag and reports a "bad
> > page table entry" in that case.
> >
> > I've removed check from lguest code and everything worked fine. Is
> > this safe from the Lguest side ?
>
> yes, should be safe. Could you send a patch so that others can apply it
> too?
>
Ofcourse :) :
Accept guest _PAGE_PWT page table entries, otherwise lguest will
always fail with a "bad page table entry" message.
Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
---
diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c
index 74b4cf2..952160b 100644
--- a/drivers/lguest/page_tables.c
+++ b/drivers/lguest/page_tables.c
@@ -178,8 +178,8 @@ static void release_pte(pte_t pte)
static void check_gpte(struct lg_cpu *cpu, pte_t gpte)
{
- if ((pte_flags(gpte) & (_PAGE_PWT|_PAGE_PSE))
- || pte_pfn(gpte) >= cpu->lg->pfn_limit)
+ if ((pte_flags(gpte) & _PAGE_PSE) ||
+ pte_pfn(gpte) >= cpu->lg->pfn_limit)
kill_guest(cpu, "bad page table entry");
}
Regards,
--
Ahmed S. Darwish
Homepage: http://darwish.07.googlepages.com
Blog: http://darwish-07.blogspot.com
next prev parent reply other threads:[~2008-02-07 0:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-06 23:21 [Lguest/x86]: Clash with ioremap_nocache() + _PAGE_PWT Ahmed S. Darwish
2008-02-06 23:59 ` Ingo Molnar
2008-02-07 0:51 ` Ahmed S. Darwish [this message]
2008-02-07 1:00 ` [PATCH] lguest: Accept guest _PAGE_PWT page table entries Ingo Molnar
2008-03-04 1:37 ` Rusty Russell
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