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Mon, 11 Jul 2022 18:56:46 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0CA704203F; Mon, 11 Jul 2022 18:56:46 +0000 (GMT) Received: from heavy.ibmuc.com (unknown [9.171.48.196]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 11 Jul 2022 18:56:45 +0000 (GMT) From: Ilya Leoshkevich To: Richard Henderson , Paolo Bonzini , Cornelia Huck , Thomas Huth , Halil Pasic , Christian Borntraeger , Eric Farman , David Hildenbrand Cc: qemu-devel@nongnu.org, qemu-s390x@nongnu.org, Ilya Leoshkevich Subject: [PATCH 1/3] accel/tcg: Fix unaligned stores to s390x low-address-protected lowcore Date: Mon, 11 Jul 2022 20:56:38 +0200 Message-Id: <20220711185640.3558813-2-iii@linux.ibm.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220711185640.3558813-1-iii@linux.ibm.com> References: <20220711185640.3558813-1-iii@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: c3j7NlnROJ8QUv6ZLR2y6FktUXmUoM3K X-Proofpoint-ORIG-GUID: iupURZyDm9hg8eBox04Puizeu-1LTMZA X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-07-11_23,2022-07-08_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 priorityscore=1501 impostorscore=0 mlxscore=0 mlxlogscore=954 lowpriorityscore=0 adultscore=0 spamscore=0 phishscore=0 suspectscore=0 clxscore=1015 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2206140000 definitions=main-2207110079 Received-SPF: pass client-ip=148.163.158.5; envelope-from=iii@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" If low-address-protection is active, unaligned stores to non-protected parts of lowcore lead to protection exceptions. The reason is that in such cases tlb_fill() call in store_helper_unaligned() covers [0, addr + size) range, which contains the protected portion of lowcore. This range is too large. The most straightforward fix would be to make sure we stay within the original [addr, addr + size) range. However, if an unaligned access affects a single page, we don't need to call tlb_fill() in store_helper_unaligned() at all, since it would be identical to the previous tlb_fill() call in store_helper(), and therefore a no-op. If an unaligned access covers multiple pages, this situation does not occur. Therefore simply skip TLB handling in store_helper_unaligned() if we are dealing with a single page. Fixes: 2bcf018340cb ("s390x/tcg: low-address protection support") Signed-off-by: Ilya Leoshkevich --- accel/tcg/cputlb.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c index f90f4312ea..a46f3a654d 100644 --- a/accel/tcg/cputlb.c +++ b/accel/tcg/cputlb.c @@ -2248,7 +2248,7 @@ store_helper_unaligned(CPUArchState *env, target_ulong addr, uint64_t val, const size_t tlb_off = offsetof(CPUTLBEntry, addr_write); uintptr_t index, index2; CPUTLBEntry *entry, *entry2; - target_ulong page2, tlb_addr, tlb_addr2; + target_ulong page1, page2, tlb_addr, tlb_addr2; MemOpIdx oi; size_t size2; int i; @@ -2256,15 +2256,17 @@ store_helper_unaligned(CPUArchState *env, target_ulong addr, uint64_t val, /* * Ensure the second page is in the TLB. Note that the first page * is already guaranteed to be filled, and that the second page - * cannot evict the first. + * cannot evict the first. An exception to this rule is PAGE_WRITE_INV + * handling: the first page could have evicted itself. */ + page1 = addr & TARGET_PAGE_MASK; page2 = (addr + size) & TARGET_PAGE_MASK; size2 = (addr + size) & ~TARGET_PAGE_MASK; index2 = tlb_index(env, mmu_idx, page2); entry2 = tlb_entry(env, mmu_idx, page2); tlb_addr2 = tlb_addr_write(entry2); - if (!tlb_hit_page(tlb_addr2, page2)) { + if (page1 != page2 && !tlb_hit_page(tlb_addr2, page2)) { if (!victim_tlb_hit(env, mmu_idx, index2, tlb_off, page2)) { tlb_fill(env_cpu(env), page2, size2, MMU_DATA_STORE, mmu_idx, retaddr); -- 2.35.3