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[2401:d006:5c08:e100:2b1d:8711:2597:136f]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-771e39cb489sm927754b3a.84.2025.08.24.17.58.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 24 Aug 2025 17:58:37 -0700 (PDT) Message-ID: Date: Mon, 25 Aug 2025 10:58:27 +1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] accel/tcg: Unify big- and little- endian atomic ops To: Danila Zhebryakov , qemu-devel@nongnu.org Cc: Chinmay Rath , Nicholas Piggin , Riku Voipio , Ilya Leoshkevich , qemu-ppc@nongnu.org, Paolo Bonzini , David Hildenbrand , qemu-s390x@nongnu.org, Laurent Vivier , Thomas Huth References: <20250821113348.91339-1-d.zhebryakov@yandex.ru> <20250821113348.91339-2-d.zhebryakov@yandex.ru> From: Richard Henderson Content-Language: en-US In-Reply-To: <20250821113348.91339-2-d.zhebryakov@yandex.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::42c; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x42c.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 8/21/25 21:33, Danila Zhebryakov wrote: > ABI_TYPE ATOMIC_NAME(cmpxchg)(CPUArchState *env, vaddr addr, > ABI_TYPE cmpv, ABI_TYPE newv, > MemOpIdx oi, uintptr_t retaddr) > { > + bool need_bswap = get_memop(oi) & MO_BSWAP; > DATA_TYPE *haddr = atomic_mmu_lookup(env_cpu(env), addr, oi, > - DATA_SIZE, retaddr); > - DATA_TYPE ret; > - > + DATA_SIZE, retaddr, &need_bswap); > + DATA_TYPE ret, ret_e; > + if (need_bswap) { I'd rather you do all of the bswap detection in the helper, not put part of it here and then modify the partial value. > diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c > index 87e14bde4f..841b54e41d 100644 > --- a/accel/tcg/cputlb.c > +++ b/accel/tcg/cputlb.c > @@ -1808,7 +1808,7 @@ static bool mmu_lookup(CPUState *cpu, vaddr addr, MemOpIdx oi, > * or io operations to proceed. Return the host address. > */ > static void *atomic_mmu_lookup(CPUState *cpu, vaddr addr, MemOpIdx oi, > - int size, uintptr_t retaddr) > + int size, uintptr_t retaddr, bool *need_bswap) > { > uintptr_t mmu_idx = get_mmuidx(oi); > MemOp mop = get_memop(oi); > @@ -1894,6 +1894,14 @@ static void *atomic_mmu_lookup(CPUState *cpu, vaddr addr, MemOpIdx oi, > notdirty_write(cpu, addr, size, full, retaddr); > } > > + if (unlikely(tlb_addr & TLB_BSWAP)) { > + assert(!( ( full->slow_flags[MMU_DATA_STORE] > + ^ full->slow_flags[MMU_DATA_LOAD ]) > + & TLB_BSWAP)); You can skip the assert. It's impossible to set a page with differing values. > + > + *need_bswap = !need_bswap; > + } This becomes mop ^= MO_BSWAP; } *need_bswap = mop & MO_BSWAP; r~