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[216.180.64.156]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7edc8679eecsm1358056a12.26.2024.10.25.10.59.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 25 Oct 2024 10:59:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1729879145; x=1730483945; darn=nongnu.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=znPbUZNNslddQtH/rLaGSWOe8DbymY8ZMMF9baiLEDo=; b=yHHVX14TBk+qTYIwxrqUH1HZ5sayggAehz0txQndHCV7cd9O3Xtt3lg/Weh/USDVe2 RBam0Q/jsyAVtJIZ0bXoCs0X2Hi09DMglSztadBJmys4q2xtItmTGjaRUVDFQzRJktTo ErHugZtpSwJ0If23fqGvQhchpDvahg4JQjNyYvhUVebqJNW/MU/nvP1kcLAPiNuqdtXs qIUw+g5bJCUwhDj9erxIaFKqcIoSNpjDbOvQMoL/aMPA+VnrZEdiRRdYZddXuqLek+fi eXH9E80Q9t0yseO6M/XH6G4jt98PDPfwpyhUrWvY9lHzV8W+294Yf0ScJtr14ugiHFCn IR2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729879145; x=1730483945; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=znPbUZNNslddQtH/rLaGSWOe8DbymY8ZMMF9baiLEDo=; b=Sixb0v88NuN9CqK1hgduhXZppBAScEXxA+1gUUTRMQp+jQ61suqXEz0XmSNS97pvMF xVwtSOAz6LYnojjk61T/CsNPqSnDiWqi7CEiY47RFHJNUOKcHCwqSFM+HLF635A4+rhe tBv8hlQ7tKNl/1lJ9ryTgzYUkgwhaW8QlSEI1EcX1BoimvFoqtzq2GYXQ0Vz/+qQtSlW W7Uwbso/dKP8x9qGL8Hv2CpEScW3Fast8I9AAWaJa3haJvQfK6L3rbZR4pOdzRuSpZ+k k6UcsVq01Dk8FmQVXmwcRB6NvEH24wZwtCUAfl1eWfV8NZrvm1RciK4PiCaRXXuXjH3M n3Lg== X-Gm-Message-State: AOJu0Yzv/Ws3Btz0Ad3IfSa1XXv5F5hrLHiOScBDcYpggQCNsJ3oqBVY z6liW8dGsyqtAhjHaEC5yeuLnm6I3khfqspVsYKY1ad/qPiDw7MkWYUgtBiUh5PtTrtcAAT3Mq+ 1SC/cEw== X-Google-Smtp-Source: AGHT+IFEIbN5ucd0K4JrZaLhNCHpSxdelyJi1BrseWQmDZDFAGld0WuhFZh0tunxTZ0e3ACllcSuEw== X-Received: by 2002:a05:6a21:1707:b0:1d9:17fa:e5d8 with SMTP id adf61e73a8af0-1d9a846a5e3mr82205637.26.1729879145415; Fri, 25 Oct 2024 10:59:05 -0700 (PDT) From: Pierrick Bouvier To: qemu-devel@nongnu.org Cc: Eduardo Habkost , Richard Henderson , Paolo Bonzini , Pierrick Bouvier Subject: [PATCH v3 1/2] target/i386: fix hang when using slow path for ptw_setl Date: Fri, 25 Oct 2024 10:58:56 -0700 Message-Id: <20241025175857.2554252-2-pierrick.bouvier@linaro.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20241025175857.2554252-1-pierrick.bouvier@linaro.org> References: <20241025175857.2554252-1-pierrick.bouvier@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2607:f8b0:4864:20::52e; envelope-from=pierrick.bouvier@linaro.org; helo=mail-pg1-x52e.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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @linaro.org) X-ZM-MESSAGEID: 1729879180596116600 Content-Type: text/plain; charset="utf-8" When instrumenting memory accesses for plugin, we force memory accesses to use the slow path for mmu [1]. This create a situation where we end up calling ptw_setl_slow. This was fixed recently in [2] but the issue still could appear out of plugins use case. Since this function gets called during a cpu_exec, start_exclusive then hangs. This exclusive section was introduced initially for security reasons [3]. I suspect this code path was never triggered, because ptw_setl_slow would always be called transitively from cpu_exec, resulting in a hang. [1] https://gitlab.com/qemu-project/qemu/-/commit/6d03226b42247b68ab2f0b366= 3e0f624335a4055 [2] https://gitlab.com/qemu-project/qemu/-/commit/115ade42d50144c15b74368d3= 2dc734ea277d853 [3] https://gitlab.com/qemu-project/qemu/-/issues/279 Fixes: https://gitlab.com/qemu-project/qemu/-/issues/2566 Signed-off-by: Pierrick Bouvier Reviewed-by: Richard Henderson --- target/i386/tcg/sysemu/excp_helper.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/target/i386/tcg/sysemu/excp_helper.c b/target/i386/tcg/sysemu/= excp_helper.c index da187c8792a..ddc51e3e0b8 100644 --- a/target/i386/tcg/sysemu/excp_helper.c +++ b/target/i386/tcg/sysemu/excp_helper.c @@ -107,6 +107,10 @@ static bool ptw_setl_slow(const PTETranslate *in, uint= 32_t old, uint32_t new) { uint32_t cmp; =20 + CPUState *cpu =3D env_cpu(in->env); + /* We are in cpu_exec, and start_exclusive can't be called directly.*/ + g_assert(cpu->running); + cpu_exec_end(cpu); /* Does x86 really perform a rmw cycle on mmio for ptw? */ start_exclusive(); cmp =3D cpu_ldl_mmuidx_ra(in->env, in->gaddr, in->ptw_idx, 0); @@ -114,6 +118,7 @@ static bool ptw_setl_slow(const PTETranslate *in, uint3= 2_t old, uint32_t new) cpu_stl_mmuidx_ra(in->env, in->gaddr, new, in->ptw_idx, 0); } end_exclusive(); + cpu_exec_start(cpu); return cmp =3D=3D old; } =20 --=20 2.39.5