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[81.250.175.67]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4279f259761sm110337535e9.11.2024.07.15.01.46.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Jul 2024 01:46:49 -0700 (PDT) From: =?utf-8?q?Cl=C3=A9ment_Chigot?= To: qemu-devel@nongnu.org Cc: npiggin@gmail.com, =?utf-8?q?Cl=C3=A9ment_Chigot?= Subject: [PATCH] hw/ppc: fix decrementer with BookE timers Date: Mon, 15 Jul 2024 10:46:39 +0200 Message-Id: <20240715084639.983127-1-chigot@adacore.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::231; envelope-from=chigot@adacore.com; helo=mail-lj1-x231.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 The BookE decrementer stops at 0, meaning that it won't decremented towards "negative" values. However, the current logic is inverted: decr is updated solely when the resulting value would be negative. Signed-off-by: Clément Chigot Fixed: 8e0a5ac87800 ("hw/ppc: Avoid decrementer rounding errors") Reviewed-by: Cédric Le Goater --- hw/ppc/ppc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c index e6fa5580c0..9fc85c7de0 100644 --- a/hw/ppc/ppc.c +++ b/hw/ppc/ppc.c @@ -729,7 +729,9 @@ static inline int64_t __cpu_ppc_load_decr(CPUPPCState *env, int64_t now, int64_t decr; n = ns_to_tb(tb_env->decr_freq, now); - if (next > n && tb_env->flags & PPC_TIMER_BOOKE) { + + /* BookE timers stop when reaching 0. */ + if (next < n && tb_env->flags & PPC_TIMER_BOOKE) { decr = 0; } else { decr = next - n;