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GET /api/1.1/patches/2231735/?format=api
{ "id": 2231735, "url": "http://patchwork.ozlabs.org/api/1.1/patches/2231735/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260501101505.3485916-14-peter.maydell@linaro.org/", "project": { "id": 14, "url": "http://patchwork.ozlabs.org/api/1.1/projects/14/?format=api", "name": "QEMU Development", "link_name": "qemu-devel", "list_id": "qemu-devel.nongnu.org", "list_email": "qemu-devel@nongnu.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20260501101505.3485916-14-peter.maydell@linaro.org>", "date": "2026-05-01T10:14:50", "name": "[PULL,13/28] target/arm/kvm: Cache host CPU probe failure", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "ca31864d0fef1fd7ace654523b3be143a3f83164", "submitter": { "id": 5111, "url": "http://patchwork.ozlabs.org/api/1.1/people/5111/?format=api", "name": "Peter Maydell", "email": "peter.maydell@linaro.org" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260501101505.3485916-14-peter.maydell@linaro.org/mbox/", "series": [ { "id": 502437, "url": "http://patchwork.ozlabs.org/api/1.1/series/502437/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=502437", "date": "2026-05-01T10:14:41", "name": "[PULL,01/28] hw/arm/fsl-imx8mp: Do not create redundant unimplemented devices", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/502437/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2231735/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2231735/checks/", "tags": {}, "headers": { "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=linaro.org header.i=@linaro.org header.a=rsa-sha256\n header.s=google header.b=oRXoGm9g;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists1p.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=patchwork.ozlabs.org)" ], "Received": [ "from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g6Rp61S9rz1xqf\n\tfor <incoming@patchwork.ozlabs.org>; Fri, 01 May 2026 20:18:38 +1000 (AEST)", "from localhost ([::1] helo=lists1p.gnu.org)\n\tby lists1p.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from <qemu-devel-bounces@nongnu.org>)\n\tid 1wIkuI-00042d-Ud; Fri, 01 May 2026 06:15:38 -0400", "from eggs.gnu.org ([2001:470:142:3::10])\n by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from <peter.maydell@linaro.org>)\n id 1wIkuA-000403-9b\n for qemu-devel@nongnu.org; Fri, 01 May 2026 06:15:30 -0400", "from mail-wm1-x329.google.com ([2a00:1450:4864:20::329])\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128)\n (Exim 4.90_1) (envelope-from <peter.maydell@linaro.org>)\n id 1wIku8-0000AB-Dh\n for qemu-devel@nongnu.org; Fri, 01 May 2026 06:15:29 -0400", "by mail-wm1-x329.google.com with SMTP id\n 5b1f17b1804b1-48984d29fe3so26211545e9.0\n for <qemu-devel@nongnu.org>; Fri, 01 May 2026 03:15:27 -0700 (PDT)", "from lanath.. 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[81.2.115.145])\n by smtp.gmail.com with ESMTPSA id\n 5b1f17b1804b1-48a8fede418sm12863335e9.6.2026.05.01.03.15.23\n for <qemu-devel@nongnu.org>\n (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n Fri, 01 May 2026 03:15:24 -0700 (PDT)" ], "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=linaro.org; s=google; t=1777630526; x=1778235326; darn=nongnu.org;\n h=content-transfer-encoding:mime-version:references:in-reply-to\n :message-id:date:subject:to:from:from:to:cc:subject:date:message-id\n :reply-to; bh=2YjxkgDmODhzB8F97AzDnOR+tGT6XYFOQgHnOUXmosQ=;\n b=oRXoGm9gk7R71IyQxNkHRQyGzFLOiB2vp5S6Ba3YLdZIh4Pe9X9T8jTjrkOWvj5vmS\n ps9FAYw5mONzDIsGcWE8nr2YqpT+ubJIFc3aG2jgGdGi5H4LOnvTXwKX1d9Oh1h5ICzx\n WpFuzt6rC0AT6/E6lepCyWnffvQYinCcYbrPA69CordLQ4GZ1jQvaIKGe7flDDGORRQl\n klTDx+9/pKlHkR7KwlASUiOKk5wP8/fVEVFbYpmxO1iFJLOOnTQo9sDKpr2T2BCBPx60\n 3Jzy1ldJYHhLV79KPf2t/6qgnBHUHQE1A9hNrRypCtmaDJegTqeXZNv1U9kNGGYX8qjQ\n 5avA==", "X-Google-DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=1e100.net; s=20251104; t=1777630526; x=1778235326;\n h=content-transfer-encoding:mime-version:references:in-reply-to\n :message-id:date:subject:to:from:x-gm-gg:x-gm-message-state:from:to\n :cc:subject:date:message-id:reply-to;\n bh=2YjxkgDmODhzB8F97AzDnOR+tGT6XYFOQgHnOUXmosQ=;\n b=aDv1rorr6OiB5jocuHs2KgYtWdWFHz1xYSY9ydhbsCIAs1lR2w2b/SkeVQXnCVBsuF\n 3ZyxO5s/1u/PHcp492LdZYbWhL0TMv1XuVt6HxXOsya4pcEqvsF0PEQ590fCOhFM4PwT\n Qw4QZreoV5yvg8guB49rHLtknp/uuUU+lWtghwfBceqa2O+bNdibA4ZcJRWQ1K3PrjUJ\n KkZEibH75VL7wTYmwV/R3lwDTp9UVhOzwuupaG53zdrCrHfuzTIRQEqRrTFu4YJqcuHr\n nty5GTJ5FkZcuex89Kr37tAd5VetDdxLSCstxbBpFD+tizEZB2Yk31R+JF0zcOXvo/9e\n vadg==", "X-Gm-Message-State": "AOJu0YwgPJ0enM35tDP8Ni4AtoAYhzJb+J6k8sBlekrubA/ddMGlJV31\n a67CuG6VMlg1VsNb2ECC7XixZwZ8Kg1wXsOmwVxdjjqwrPJI49VK85EcMY/MdLW02jBtZv60EMT\n mn3oi", "X-Gm-Gg": "AeBDieuJSAUvPA5HFCUNUpjhyPuuEIZo77GjAHyOxU9AaeOHrTj0IE1wcG0CdK7IDi6\n I7pGYMoKEnRZU8uQWYrczUDT4z4W0vCh5zRedEmHtvs8VLaE9JMRuqE/aCb199KtlbAQAbUFU31\n L+cg2Z4Dv2L9+KMSpcKa2XXB03B9PKIYMIUouNPT3Z9HuD8O9X59u1Rrwbreu86Pe9C4mMldqIa\n Z5f8PCg1thEIUAiOjmRBDZY+YhgljmLCvLDsZtOPuN8+jtptrvaIvwde+R10Pr6rtjmnjkN1DFm\n BNqGHdU9cZGNpOSbh/BC9PPv72RL7U0HN4+nxZynMvPqijPNg4r58yC70KJIyraFqmPR7ssMchR\n lAvkd0GVu1jTSjNmbgzvhdtGnEoUAOCIEJYq1quxdSzC29XgQuuGnhGO/LUzqMdic9MetjwOBCp\n uecWzCjL6dULIcbh+dR+PGJULSaNLWR7WBhPxWUrGIAVfi17KcZMUCaxr26RzwRf9FOm0891Jdy\n UE9SRYC5TruEBpHUFxgficQEYR7yXz9YfrjScpCe2uUlhqxruFg", "X-Received": "by 2002:a05:600c:1d1a:b0:485:30d4:6b9e with SMTP id\n 5b1f17b1804b1-48a84458d16mr114107105e9.21.1777630526469;\n Fri, 01 May 2026 03:15:26 -0700 (PDT)", "From": "Peter Maydell <peter.maydell@linaro.org>", "To": "qemu-devel@nongnu.org", "Subject": "[PULL 13/28] target/arm/kvm: Cache host CPU probe failure", "Date": "Fri, 1 May 2026 11:14:50 +0100", "Message-ID": "<20260501101505.3485916-14-peter.maydell@linaro.org>", "X-Mailer": "git-send-email 2.43.0", "In-Reply-To": "<20260501101505.3485916-1-peter.maydell@linaro.org>", "References": "<20260501101505.3485916-1-peter.maydell@linaro.org>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "Received-SPF": "pass client-ip=2a00:1450:4864:20::329;\n envelope-from=peter.maydell@linaro.org; helo=mail-wm1-x329.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,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001,\n 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": "qemu development <qemu-devel.nongnu.org>", "List-Unsubscribe": "<https://lists.nongnu.org/mailman/options/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>", "List-Archive": "<https://lists.nongnu.org/archive/html/qemu-devel>", "List-Post": "<mailto:qemu-devel@nongnu.org>", "List-Help": "<mailto:qemu-devel-request@nongnu.org?subject=help>", "List-Subscribe": "<https://lists.nongnu.org/mailman/listinfo/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=subscribe>", "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org", "Sender": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org" }, "content": "From: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>\n\nkvm_arm_set_cpu_features_from_host() does not properly handle host CPU\nprobe failure with caching. The current algorithm can be summarized as\nfollows:\n\n If dtb_compatible is not cached:\n If kvm_arm_create_scratch_host_vcpu() fails:\n Report failure\n\n Cache dtb_compatible\n\n If getting register values fails:\n Report failure\n\n Report success\n\nThis algorithm has the following problems:\n\n- If kvm_arm_create_scratch_host_vcpu() fails, probing may be repeated.\n- If getting register values fails, later invocations incorrectly report\n success.\n\nMake two changes to fix them:\n\n- Cache dtb_compatible whenever a probe is attempted.\n- Record probe failure by assigning QEMU_KVM_ARM_TARGET_NONE to\n arm_host_cpu_features.target.\n\nSuggested-by: Peter Maydell <peter.maydell@linaro.org>\nSigned-off-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>\nReviewed-by: Peter Maydell <peter.maydell@linaro.org>\nMessage-id: 20260428-features-v1-1-1841b39da7e6@rsg.ci.i.u-tokyo.ac.jp\nSigned-off-by: Peter Maydell <peter.maydell@linaro.org>\n---\n target/arm/kvm.c | 38 ++++++++++++++++++++++----------------\n 1 file changed, 22 insertions(+), 16 deletions(-)", "diff": "diff --git a/target/arm/kvm.c b/target/arm/kvm.c\nindex d4a68874b8..7d194ea112 100644\n--- a/target/arm/kvm.c\n+++ b/target/arm/kvm.c\n@@ -273,7 +273,7 @@ static uint32_t kvm_arm_sve_get_vls(int fd)\n return vls[0] & MAKE_64BIT_MASK(0, ARM_MAX_VQ);\n }\n \n-static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)\n+static void kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)\n {\n /* Identify the feature bits corresponding to the host CPU, and\n * fill out the ARMHostCPUClass fields accordingly. To do this\n@@ -287,6 +287,13 @@ static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)\n uint64_t features = 0;\n int err;\n \n+ ahcf->target = QEMU_KVM_ARM_TARGET_NONE;\n+ ahcf->dtb_compatible = \"arm,armv8\";\n+\n+ if (!kvm_enabled()) {\n+ return;\n+ }\n+\n /*\n * target = -1 informs kvm_arm_create_scratch_host_vcpu()\n * to use the preferred target\n@@ -326,11 +333,9 @@ static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)\n }\n \n if (!kvm_arm_create_scratch_host_vcpu(fdarray, &init)) {\n- return false;\n+ return;\n }\n \n- ahcf->target = init.target;\n- ahcf->dtb_compatible = \"arm,armv8\";\n int fd = fdarray[2];\n \n err = get_host_cpu_reg(fd, ahcf, ID_AA64PFR0_EL1_IDX);\n@@ -454,7 +459,7 @@ static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)\n kvm_arm_destroy_scratch_host_vcpu(fdarray);\n \n if (err < 0) {\n- return false;\n+ return;\n }\n \n /*\n@@ -471,9 +476,8 @@ static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)\n features |= 1ULL << ARM_FEATURE_EL2;\n }\n \n+ ahcf->target = init.target;\n ahcf->features = features;\n-\n- return true;\n }\n \n void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)\n@@ -481,18 +485,20 @@ void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)\n CPUARMState *env = &cpu->env;\n \n if (!arm_host_cpu_features.dtb_compatible) {\n- if (!kvm_enabled() ||\n- !kvm_arm_get_host_cpu_features(&arm_host_cpu_features)) {\n- /* We can't report this error yet, so flag that we need to\n- * in arm_cpu_realizefn().\n- */\n- cpu->kvm_target = QEMU_KVM_ARM_TARGET_NONE;\n- cpu->host_cpu_probe_failed = true;\n- return;\n- }\n+ kvm_arm_get_host_cpu_features(&arm_host_cpu_features);\n }\n \n cpu->kvm_target = arm_host_cpu_features.target;\n+\n+ if (cpu->kvm_target == QEMU_KVM_ARM_TARGET_NONE) {\n+ /*\n+ * We can't report this error yet, so flag that we need to\n+ * in arm_cpu_realizefn().\n+ */\n+ cpu->host_cpu_probe_failed = true;\n+ return;\n+ }\n+\n cpu->dtb_compatible = arm_host_cpu_features.dtb_compatible;\n cpu->isar = arm_host_cpu_features.isar;\n cpu->sve_vq.supported = arm_host_cpu_features.sve_vq_supported;\n", "prefixes": [ "PULL", "13/28" ] }