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Iglesias" References: <20200825205950.730499-1-richard.henderson@linaro.org> <20200825205950.730499-65-richard.henderson@linaro.org> <20200827092413.GL2954729@toto> From: Richard Henderson Message-ID: <7e242b2a-d582-059c-f282-9e001653b627@linaro.org> Date: Thu, 27 Aug 2020 02:58:06 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200827092413.GL2954729@toto> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::1043; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x1043.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 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, NICE_REPLY_A=-2.239, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 8/27/20 2:24 AM, Edgar E. Iglesias wrote: >> + /* >> + * Instruction access memory barrier. >> + * End the TB so that we recognize self-modified code immediately. >> + */ >> + if (mbar_imm & 1) { >> + dc->cpustate_changed = 1; >> + } > > This should be (mbar_imm & 1) == 0 > But even with that fixed it fails some of our tests because interrupts > that should become visible within a couple of cycles after a > memory data barrier can now be delayed longer. > > I think we should always break the TB. Ok. I assume this follows a write to something like an interrupt controller register? > >> + /* Data access memory barrier. */ >> + if (mbar_imm & 2) { >> + tcg_gen_mb(TCG_BAR_SC | TCG_MO_ALL); >> + } > > This should be (mbar_imm & 2) == 0 Oops. ;-) Applying the following incremental patch. r~ diff --git a/target/microblaze/translate.c b/target/microblaze/translate.c index a391e80fb9..1e2bb529ac 100644 --- a/target/microblaze/translate.c +++ b/target/microblaze/translate.c @@ -1170,16 +1170,8 @@ static bool trans_mbar(DisasContext *dc, arg_mbar *arg) { int mbar_imm = arg->imm; - /* - * Instruction access memory barrier. - * End the TB so that we recognize self-modified code immediately. - */ - if (mbar_imm & 1) { - dc->cpustate_changed = 1; - } - /* Data access memory barrier. */ - if (mbar_imm & 2) { + if ((mbar_imm & 2) == 0) { tcg_gen_mb(TCG_BAR_SC | TCG_MO_ALL); } @@ -1204,6 +1196,19 @@ static bool trans_mbar(DisasContext *dc, arg_mbar *arg) gen_raise_exception(dc, EXCP_HLT); } + + /* + * If !(mbar_imm & 1), this is an instruction access memory barrier + * and we need to end the TB so that we recognize self-modified + * code immediately. + * + * However, there are some data mbars that need the TB break + * (and return to main loop) to recognize interrupts right away. + * E.g. recognizing a change to an interrupt controller register. + * + * Therefore, choose to end the TB always. + */ + dc->cpustate_changed = 1; return true; }