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([2804:431:c7c7:f4d8:aa07:335f:99e0:a6e7]) by smtp.gmail.com with ESMTPSA id j124sm27565555qkd.98.2022.01.03.13.50.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Jan 2022 13:50:12 -0800 (PST) Message-ID: <25b90f46-befa-3fc9-cdef-e6e999765f33@gmail.com> Date: Mon, 3 Jan 2022 18:50:09 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH v2 4/5] target/ppc: keep ins_cnt/cyc_cnt cleared if MMCR0_FC is set Content-Language: en-US To: Richard Henderson , qemu-devel@nongnu.org References: <20220103185332.117878-1-danielhb413@gmail.com> <20220103185332.117878-5-danielhb413@gmail.com> <0b9b2a07-4b0c-4095-9365-d95139e182fc@linaro.org> From: Daniel Henrique Barboza In-Reply-To: <0b9b2a07-4b0c-4095-9365-d95139e182fc@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 2607:f8b0:4864:20::82c (failed) Received-SPF: pass client-ip=2607:f8b0:4864:20::82c; envelope-from=danielhb413@gmail.com; helo=mail-qt1-x82c.google.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, NICE_REPLY_A=-3.354, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: , Cc: qemu-ppc@nongnu.org, clg@kaod.org, david@gibson.dropbear.id.au Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 1/3/22 18:38, Richard Henderson wrote: > On 1/3/22 10:53 AM, Daniel Henrique Barboza wrote: >> pmu_update_summaries() is not considering the case where the PMU can be >> turned off (i.e. stop counting all events) if MMCR0_FC is set, >> regardless of the other frozen counter bits state. This use case was >> covered in the late pmc_get_event(), via the also gone pmc_is_inactive(), >> that would return an invalid event if MMCR0_FC was set. >> >> This use case is exercised by the back_to_back_ebbs_test Linux kernel >> selftests [1]. As it is today, after enabling EBB exceptions, the test >> will report an additional event-based branch being taken and will fail. >> Other tests, such as cycles_test.c, will report additional cycles being >> calculated in the counters because we're not freezing the PMU quick >> enough. >> >> Fix pmu_update_summaries() by keeping env->ins_cnt and env->cyc_cnt >> cleared when MMCR0_FC is set. >> >> [1] tools/testing/selftests/powerpc/pmu/ebb/back_to_back_ebbs_test.c >> >> Signed-off-by: Daniel Henrique Barboza >> --- >>   target/ppc/power8-pmu.c | 5 +++++ >>   1 file changed, 5 insertions(+) >> >> diff --git a/target/ppc/power8-pmu.c b/target/ppc/power8-pmu.c >> index 7fc7d91109..73713ca2a3 100644 >> --- a/target/ppc/power8-pmu.c >> +++ b/target/ppc/power8-pmu.c >> @@ -40,6 +40,10 @@ void pmu_update_summaries(CPUPPCState *env) >>       int ins_cnt = 0; >>       int cyc_cnt = 0; >> +    if (mmcr0 & MMCR0_FC) { >> +        goto hflags_calc; >> +    } >> + >>       if (!(mmcr0 & MMCR0_FC14) && mmcr1 != 0) { >>           target_ulong sel; >> @@ -71,6 +75,7 @@ void pmu_update_summaries(CPUPPCState *env) >>       ins_cnt |= !(mmcr0 & MMCR0_FC56) << 5; >>       cyc_cnt |= !(mmcr0 & MMCR0_FC56) << 6; >> + hflags_calc: > > Good catch, but should be folded into patch 1 to avoid bisection breakage. Fair point. Given that you have a suggestion in patch 5 as well I'll send a v3. Thanks, Daniel > > > r~