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([71.212.136.242]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2ea024a49a8sm3362274a91.23.2024.11.15.12.58.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Nov 2024 12:58:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1731704336; x=1732309136; 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=uCYl3p7NTkXg+Dt0eWVy+0t6Rq+HCybUm/IWs0g2j0w=; b=wfhPx2vTByQTb44lBMOctLqutMGfiuRzTnOzG4JdkqTPkSmcOaUQiBaq1luVmLsw7i ocjh3GF0vaGC+XrJIYRB2vu5dVCXkXFhDtLDHFlV9bYOHSYJZaqbOyXiQhAVk/6M8g9f An+ENYhj1W1Qip4QKKdcQ1KOYHB9nvy2Ud5auxAlECabPuG+o3auVaGMnosH6rxOOVev 6pS1aKEkMw66GCptMcHnmshqQV7D7GP5e0JFo2Bwsu+mcIcmQATjfdR6ELWenAqAOW85 YaanYLKM2KUZ85Ht0+CQ+bcB6Rgf8Bs/2G+y9ccVabneTouE2lusct/Y4dVq0Uoh4yhI xRgg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1731704336; x=1732309136; 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=uCYl3p7NTkXg+Dt0eWVy+0t6Rq+HCybUm/IWs0g2j0w=; b=nJENQXH4lpnPvICsPDWipPOsjoOq6Wjy2YJgwoBK02eaFEXf5RsHGzQ7PUxSAFcmoc Bviu53ADsHFQdhhed381FMkWbH57MKE2aX/ICspy4ZBImEpvpXdws+cRs5Bg94PKSuQX RlHdPLTkmwhw/UIoSVwVu554EczIeVkOTYBpfjBVcvziyiXMrPI+3kYpvlsOp0R9BY5R XX51F6AqjRgZTDlA/CqfnClzp6lT4G3T16XF+ZwPF/ldKlj6H/VIRylEKf22WZkf72CG +pmiEGnA3xXubrpizmMDeKKpKGJAm3OESBNxOEQuqlNQ4UpnVT8Kw7cjN94DRh3pdJpQ uqVQ== X-Gm-Message-State: AOJu0YxB96/O6ei9Z0v8sQoHqWnThuuEmH3y9ZIVT4exShWerT1lStHd dnq7yuvoTktBk0EVPW+/uB/BU1IyDBS5pCsz8h7Lu8sJ1VLps15IFLLKaLXImQOXWliOiACF6SI E X-Google-Smtp-Source: AGHT+IGefY/UTFTE1dTr55aBICS8jh/mvG5H2HvXhRnSDB0lNKb8JV1m0Hz69e0xGzSmQbmVtd9xRw== X-Received: by 2002:a17:90b:4c52:b0:2e9:4717:97a8 with SMTP id 98e67ed59e1d1-2ea1559feb9mr4091044a91.36.1731704336337; Fri, 15 Nov 2024 12:58:56 -0800 (PST) From: Richard Henderson To: qemu-devel@nongnu.org Cc: Pierrick Bouvier Subject: [PULL 05/14] target/i386: fix hang when using slow path for ptw_setl Date: Fri, 15 Nov 2024 12:58:40 -0800 Message-ID: <20241115205849.266094-6-richard.henderson@linaro.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241115205849.266094-1-richard.henderson@linaro.org> References: <20241115205849.266094-1-richard.henderson@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::52a; envelope-from=richard.henderson@linaro.org; helo=mail-pg1-x52a.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: 1731704530063116601 Content-Type: text/plain; charset="utf-8" From: Pierrick Bouvier 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 Message-ID: <20241025175857.2554252-2-pierrick.bouvier@linaro.org> Signed-off-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 02d3486421..b1f40040f8 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 2.43.0