H_ENTER hcall handling in qemu had assumptions that a cache inhibited
hpte entry won't have memory conference set. Also older kernel
mentioned that some version of pHyp required this (the code removed
by the below commit says:
/* Make pHyp happy */
if ((rflags & _PAGE_NO_CACHE) && !(rflags & _PAGE_WRITETHRU))
hpte_r &= ~HPTE_R_M;
But with older kernel we had some inconsistent memory conherence
mapping. We always enabled memory conherence in the page fault path and
removed memory conherence is _PAGE_NO_CACHE was set when we mapped the
page via htab_bolt_mapping. The commit mentioned below tried to
consolidate that by always enabling memory conherence. But as mentioned
above that breaks Qemu H_ENTER handling.
This patch update this such that we enable memory conherence only if
cache inhibited is not set and bring fault handling, lpar and bolt
mapping in sync.
Fixes: commit 30bda41aba4e("powerpc/mm: Drop WIMG in favour of new constant")
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
---
arch/powerpc/mm/hash_utils_64.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index fcf676f7f522..32bf92d2e7ff 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -201,9 +201,8 @@ unsigned long htab_convert_pte_flags(unsigned long pteflags)
/*
* We can't allow hardware to update hpte bits. Hence always
* set 'R' bit and set 'C' if it is a write fault
- * Memory coherence is always enabled
*/
- rflags |= HPTE_R_R | HPTE_R_M;
+ rflags |= HPTE_R_R;
if (pteflags & _PAGE_DIRTY)
rflags |= HPTE_R_C;
@@ -213,10 +212,15 @@ unsigned long htab_convert_pte_flags(unsigned long
pteflags)
if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_TOLERANT)
rflags |= HPTE_R_I;
- if ((pteflags & _PAGE_CACHE_CTL ) == _PAGE_NON_IDEMPOTENT)
+ else if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_NON_IDEMPOTENT)
rflags |= (HPTE_R_I | HPTE_R_G);
- if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_SAO)
- rflags |= (HPTE_R_I | HPTE_R_W);
+ else if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_SAO)
+ rflags |= (HPTE_R_W | HPTE_R_I | HPTE_R_M);
+ else
+ /*
+ * Add memory coherence if cache inhibited is not set
+ */
+ rflags |= HPTE_R_M;
return rflags;
}
--
2.7.4
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