[Lguest] bad page state
Rusty Russell
rusty at rustcorp.com.au
Wed Jul 23 09:20:10 EST 2008
On Tuesday 22 July 2008 23:42:58 Matias Zabaljauregui wrote:
> Hello, after trying several configurations, I cannot make lguest work
> (2.6.26).
> Maybe someone can glance at it and save me more hours of recompiling :)
> Thank you in advance.
Yes, here's the fix:
x86: fix pte_flags() to only return flags, fix lguest.
Change a15af1c9ea2750a9ff01e51615c45950bad8221b 'x86/paravirt: add
pte_flags to just get pte flags' removed lguest's private pte_flags()
in favor of a generic one.
Unfortunately, the generic one doesn't filter out the non-flags bits:
this results in lguest creating corrupt shadow page tables and blowing
up host memory.
Since noone is supposed to use the pfn part of pte_flags(), it seems
safest to always do the filtering.
Cc: Jeremy Fitzhardinge <jeremy at goop.org>
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
---
arch/x86/kernel/paravirt.c | 2 +-
include/asm-x86/page.h | 7 ++++++-
include/asm-x86/paravirt.h | 3 +++
3 files changed, 10 insertions(+), 2 deletions(-)
diff -r ee1a6adad3d2 arch/x86/kernel/paravirt.c
--- a/arch/x86/kernel/paravirt.c Mon Jul 21 12:49:25 2008 +1000
+++ b/arch/x86/kernel/paravirt.c Tue Jul 22 15:31:04 2008 +1000
@@ -428,7 +428,7 @@ struct pv_mmu_ops pv_mmu_ops = {
#endif /* PAGETABLE_LEVELS >= 3 */
.pte_val = native_pte_val,
- .pte_flags = native_pte_val,
+ .pte_flags = native_pte_flags,
.pgd_val = native_pgd_val,
.make_pte = native_make_pte,
diff -r ee1a6adad3d2 include/asm-x86/page.h
--- a/include/asm-x86/page.h Mon Jul 21 12:49:25 2008 +1000
+++ b/include/asm-x86/page.h Tue Jul 22 15:31:04 2008 +1000
@@ -144,6 +144,11 @@ static inline pteval_t native_pte_val(pt
return pte.pte;
}
+static inline pteval_t native_pte_flags(pte_t pte)
+{
+ return native_pte_val(pte) & ~PTE_MASK;
+}
+
#define pgprot_val(x) ((x).pgprot)
#define __pgprot(x) ((pgprot_t) { (x) } )
@@ -165,7 +170,7 @@ static inline pteval_t native_pte_val(pt
#endif
#define pte_val(x) native_pte_val(x)
-#define pte_flags(x) native_pte_val(x)
+#define pte_flags(x) native_pte_flags(x)
#define __pte(x) native_make_pte(x)
#endif /* CONFIG_PARAVIRT */
diff -r ee1a6adad3d2 include/asm-x86/paravirt.h
--- a/include/asm-x86/paravirt.h Mon Jul 21 12:49:25 2008 +1000
+++ b/include/asm-x86/paravirt.h Tue Jul 22 15:31:04 2008 +1000
@@ -1083,6 +1083,9 @@ static inline pteval_t pte_flags(pte_t p
ret = PVOP_CALL1(pteval_t, pv_mmu_ops.pte_flags,
pte.pte);
+#ifdef CONFIG_PARAVIRT_DEBUG
+ BUG_ON(ret & PTE_MASK);
+#endif
return ret;
}
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