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 097d8a6797fa8142882d817a5221419cf4aeb591..94da4d52d798e8490f21c59c777df72d6bba86d5 100644 (file)
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -443,7 +443,7 @@ 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 --git a/include/asm-x86/page.h b/include/asm-x86/page.h
index 28d7b4533b1a63fc1c54dc9f69a0db326e3a16f7..05d9bea2bfd5f37386a040649cc0c5c4c7585df4 100644 (file)
--- a/include/asm-x86/page.h
+++ b/include/asm-x86/page.h
@@ -144,6 +144,11 @@ static inline pteval_t native_pte_val(pte_t pte)
        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(pte_t pte)
 #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 aec9767836b6cb4a9d90cc31a33d87e7ea4fc774..5ca4639dc7dd0870a51e8240bea0f7a7e542d8df 100644 (file)
--- a/include/asm-x86/paravirt.h
+++ b/include/asm-x86/paravirt.h
@@ -1088,6 +1088,9 @@ static inline pteval_t pte_flags(pte_t pte)
                ret = PVOP_CALL1(pteval_t, pv_mmu_ops.pte_flags,
                                 pte.pte);
 
+#ifdef CONFIG_PARAVIRT_DEBUG
+       BUG_ON(ret & PTE_MASK);
+#endif
        return ret;
 }