x86: fix pte_flags() to only return flags, fix lguest (updated)
(Jeremy said:
rusty: use PTE_MASK
rusty: use PTE_MASK
rusty: use PTE_MASK
When I asked:
jsgf: does that include the NX flag?
He responded eloquently:
rusty: use PTE_MASK
rusty: use PTE_MASK
yes, it's the official constant of masking flags out of ptes
)
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.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-and-morning-tea-spilled-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 097d8a6..94da4d52 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -443,7 +443,7 @@
#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 --git a/include/asm-x86/page.h b/include/asm-x86/page.h
index 28d7b45..05d9bea 100644
--- a/include/asm-x86/page.h
+++ b/include/asm-x86/page.h
@@ -144,6 +144,11 @@
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 @@
#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 --git a/include/asm-x86/paravirt.h b/include/asm-x86/paravirt.h
index aec9767..5ca4639 100644
--- a/include/asm-x86/paravirt.h
+++ b/include/asm-x86/paravirt.h
@@ -1088,6 +1088,9 @@
ret = PVOP_CALL1(pteval_t, pv_mmu_ops.pte_flags,
pte.pte);
+#ifdef CONFIG_PARAVIRT_DEBUG
+ BUG_ON(ret & PTE_MASK);
+#endif
return ret;
}