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[S390] fix page change underindication in pgste_update_all
This patch makes sure we don't underindicate _PAGE_CHANGED in case we have a race between an operation that changes the page and this code path that hits us between page_get_storage_key and page_set_storage_key. Note that we still have a potential underindication on _PAGE_REFERENCED in the unlikely event that the page was changed but not referenced _and_ someone references the page in the race window. That's not considered to be a problem. Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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1 changed files with 4 additions and 4 deletions
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@ -599,10 +599,10 @@ static inline pgste_t pgste_update_all(pte_t *ptep, pgste_t pgste)
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skey = page_get_storage_key(address);
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bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
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/* Clear page changed & referenced bit in the storage key */
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if (bits) {
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skey ^= bits;
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page_set_storage_key(address, skey, 1);
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}
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if (bits & _PAGE_CHANGED)
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page_set_storage_key(address, skey ^ bits, 1);
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else if (bits)
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page_reset_referenced(address);
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/* Transfer page changed & referenced bit to guest bits in pgste */
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pgste_val(pgste) |= bits << 48; /* RCP_GR_BIT & RCP_GC_BIT */
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/* Get host changed & referenced bits from pgste */
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