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Tue, 27 Aug 2024 08:51:12 -0700 (PDT) Message-ID: <1db29701-e4f3-4376-b79d-cb7ea303a129@linaro.org> Date: Tue, 27 Aug 2024 17:51:10 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] hw/ppc: fix decrementer with BookE timers To: =?UTF-8?Q?Cl=C3=A9ment_Chigot?= , qemu-devel@nongnu.org Cc: npiggin@gmail.com, Daniel Henrique Barboza , qemu-ppc@nongnu.org, =?UTF-8?Q?C=C3=A9dric_Le_Goater?= References: <20240715084639.983127-1-chigot@adacore.com> Content-Language: en-US From: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::22e; envelope-from=philmd@linaro.org; helo=mail-lj1-x22e.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, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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 Adding Cédric On 27/8/24 13:49, Clément Chigot wrote: > Hey, > > Gentle ping > > Thanks Clément > > On Mon, Jul 29, 2024 at 10:33 AM Clément Chigot wrote: >> >> Hi, >> >> Gentle ping + CC missing maintainers. >> >> Thanks Clément >> >> On Mon, Jul 15, 2024 at 10:46 AM Clément Chigot wrote: >>> >>> 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") >>> --- >>> 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; >>> -- >>> 2.25.1 >>> >