From nobody Sat Nov 23 21:09:46 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=linaro.org ARC-Seal: i=1; a=rsa-sha256; t=1729878842; cv=none; d=zohomail.com; s=zohoarc; b=V5YJR7YBrp9BHvujeFVzafoFGO6s5NZ/MLmVG+i6RiHH5SHDI4gJd9TqCUx8Udcxob9WEeQC2GHxzRXbfJjPudmcHXWp8K7G66OBVE54aZltLDnAUTCyO68UFOcFjtDQQUcBmDzAZQxr4gdNU3mszXh/RUE5mwvZx+ZVBJfC1k4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1729878842; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=UQVMbrxmPIorIA9abFZvz/SY8sgoMq+7si1O9+uYYos=; b=MElLwmfjrcqq+Rb3BlNMHRLTRvDzP72FY3VVVe5+Oh5GHegAGDtc+FXORxzFWFz7ca3qyvyPP7VjlKkrlnAsSZq+AqAkPqSySHbfM35NP+o9t7McJtpUoenwsQuBWY/qo2TxO5AogTdAQn19xBIoBFPnLjFLHwY8AQl18nbqgGc= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1729878842665572.3794955157939; Fri, 25 Oct 2024 10:54:02 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t4OVQ-0000iC-30; Fri, 25 Oct 2024 13:53:48 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1t4OVO-0000hv-T6 for qemu-devel@nongnu.org; Fri, 25 Oct 2024 13:53:46 -0400 Received: from mail-pf1-x434.google.com ([2607:f8b0:4864:20::434]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1t4OVN-0001fr-66 for qemu-devel@nongnu.org; Fri, 25 Oct 2024 13:53:46 -0400 Received: by mail-pf1-x434.google.com with SMTP id d2e1a72fcca58-71e49ef3bb9so1556629b3a.1 for ; Fri, 25 Oct 2024 10:53:43 -0700 (PDT) Received: from linaro.. (216-180-64-156.dyn.novuscom.net. [216.180.64.156]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-72057a3cf5asm1329416b3a.201.2024.10.25.10.53.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 25 Oct 2024 10:53:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1729878823; x=1730483623; 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=UQVMbrxmPIorIA9abFZvz/SY8sgoMq+7si1O9+uYYos=; b=Nd4S9TYeajJt7aklvplgzFkIFScQPqb52dRsujXV6R8nLK/l1X9yp6CxX7nD8lC59e qDFSaLT3Sms6ovAtznxFMi5MLpPDhKCa0qe9j2VoDwTioFJ0f1VDG+wMyIZUicFHwfEs FD4cYjA8+9WsXILKzNYgGZUIpF5sBq04maPKPSBmv+Z8OlSE9IdQc7EjP3GiEkjhwPXl sXlGmkslB1FPZrpcdaKDA2tNPk+vQULe/u60zXa3QbNk06HYlpGKWNe14pCqFbCSwKDj 2SPg7iuHImHTRl3W3c8mC+rtRn7P51EsjoiiiFvJSa74wC43N6J2bjKwHr7xAsrGyG9f p+Og== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729878823; x=1730483623; 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=UQVMbrxmPIorIA9abFZvz/SY8sgoMq+7si1O9+uYYos=; b=oxmTX5ctvtsHzdEeHEkdSO+PO+FsK+OJaEdSk62T0TpMo38gNlGTI9YKPUrlOzLxol tkO3BHulbfyfByet6wBlTf0QRpdr+47RxerkfNm+mJLZUHV0vwZpWg36hXY/b3j+Mf+D 9TaRMCyFp+KGNJmFcbf7UaVwMB9gLoTE8V9O3vcmlHHRrRZ17cI61L8flq0Ob6X2+DDZ Q5VOyHv8Pxy0+zoIUiBWIoKvEZ2gl7AfpwX8vH0y2I8QAbsRVRg98rx8YGAcpV+O0TNq Kz09Y8vlN6k1OIWh1HQrS3jwpnXA43+AIIQmbOTmid0/C4+QAfezFshrmC6OZQihF1J9 hVEg== X-Gm-Message-State: AOJu0Yw5NuhfuQK0Jsth4UMQlxmj0Ulol/0MOigAY/v3+niEAxr2UjrI YTiwn7O/hNvEkdEUzQ0hWN3+zikszqLTgV6IyIc/tDunxzfG5aEl4xwQgi3Y2uCpsAdK3eyT/sn yv6RVAg== X-Google-Smtp-Source: AGHT+IFa0E+hsTawLWlHSPtBNM5P64GPpZnPdzRdzf4sVXpXdb3PZxCb+sbtHj404ioZoQjyDyMAUA== X-Received: by 2002:a05:6a00:2e26:b0:71e:5573:8dcd with SMTP id d2e1a72fcca58-72062f1ed40mr548084b3a.2.1729878822762; Fri, 25 Oct 2024 10:53:42 -0700 (PDT) From: Pierrick Bouvier To: qemu-devel@nongnu.org Cc: Richard Henderson , Paolo Bonzini , Eduardo Habkost , Pierrick Bouvier Subject: [PATCH v2 1/2] target/i386: fix hang when using slow path for ptw_setl Date: Fri, 25 Oct 2024 10:53:33 -0700 Message-Id: <20241025175334.2549425-2-pierrick.bouvier@linaro.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20241025175334.2549425-1-pierrick.bouvier@linaro.org> References: <20241025175334.2549425-1-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::434; envelope-from=pierrick.bouvier@linaro.org; helo=mail-pf1-x434.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: 1729878843148116600 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. Since this function gets called during a cpu_exec, start_exclusive then hangs. This exclusive section was introduced initially for security reasons [2]. 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/-/issues/279 Fixes: https://gitlab.com/qemu-project/qemu/-/issues/2566 Signed-off-by: Pierrick Bouvier --- target/i386/tcg/sysemu/excp_helper.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/target/i386/tcg/sysemu/excp_helper.c b/target/i386/tcg/sysemu/= excp_helper.c index da187c8792a..e0436c7a672 100644 --- a/target/i386/tcg/sysemu/excp_helper.c +++ b/target/i386/tcg/sysemu/excp_helper.c @@ -107,6 +107,9 @@ static bool ptw_setl_slow(const PTETranslate *in, uint3= 2_t old, uint32_t new) { uint32_t cmp; =20 + /* We are in cpu_exec, and start_exclusive can't be called directly.*/ + g_assert(current_cpu && current_cpu->running); + cpu_exec_end(current_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 +117,7 @@ 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(current_cpu); return cmp =3D=3D old; } =20 --=20 2.39.5