From patchwork Thu Apr 20 12:33:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 13218723 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 25040C77B73 for ; Thu, 20 Apr 2023 12:35:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=Xon3GXxnRw3zd91v8QqqoXss5BuZE3XfUD5jODMfO8E=; b=QxVwdbKPTQG/XV 5d2RTutkICJBFR93TGKDGeYaTz0DGP6hWkyNBVTVboYRHoN+HMjVpRRS7bn4n1AeaYe1KJwAWWLP7 cPehZDHezr1I5JjqlP204mnL4N1zG8c9WTnoHmzlp/jm+km/q5M8SIb+W0jNWCzTenTBM50fBDN8U bA+CzlUqb9jQik8vveWhrycDX0Xw34RuBPf1hVnWwwpkOO3oDPOCnUwBjH8dhVGYCNTlZUjiGsl78 wi+9T9I+6Pge1HNClq+of+5j3WHC7oksinLjWMvZ14gt4lwJNSwq8T8lmPkh8IfxOtpIudsfNXBCg EmbT+5NCPrsI9kYaLUOA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1ppTUM-0084x7-2h; Thu, 20 Apr 2023 12:34:14 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1ppTUJ-0084w2-2Z for linux-arm-kernel@lists.infradead.org; Thu, 20 Apr 2023 12:34:13 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C802260A5F; Thu, 20 Apr 2023 12:34:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8FCEC433D2; Thu, 20 Apr 2023 12:34:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1681994050; bh=7ji0lagJ7ijHZrP8tFBwzs3hP3ERKCIT12K7wbpto88=; h=From:To:Cc:Subject:Date:From; b=lhLoeOmCs/o9fS5qGOrI9dDoxtnlbzKTSZ1Wz7VP90dvc52jCqIHqpTBFouaqdRSB G31CY4Zz972I+INncKIUJsa2YOijj+zQba5PG/kh+242qLxej83qWMGZjY0hfHkb+F ig11XmMBhawRKR9scTi6Xd0SUOFhRZKHTIm2wrjBPzj7uoCK+Iu+v1N4K4+TNCmHtX k5HwEgHBsPMUt3M+vQf4MbtNW5FzgK21gTeRjxC0eJtNuyedXcOoHpe3HDNX21theD ogAZKxpC9GWb4HkOEqJ5kqynoLRbVtg0EJV1Ky7l7F12ltYxrJlhriH3VsJSeMSDLU R2pj2SY/nwgRQ== From: Will Deacon To: linux-arm-kernel@lists.infradead.org Cc: kvmarm@lists.linux.dev, Will Deacon , Oliver Upton , Fuad Tabba , Marc Zyngier Subject: [PATCH] KVM: arm64: Ensure CPU PMU probes before pKVM host de-privilege Date: Thu, 20 Apr 2023 13:33:56 +0100 Message-Id: <20230420123356.2708-1-will@kernel.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230420_053411_934537_C403B455 X-CRM114-Status: GOOD ( 22.01 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Although pKVM supports CPU PMU emulation for non-protected guests since 722625c6f4c5 ("KVM: arm64: Reenable pmu in Protected Mode"), this relies on the PMU driver probing before the host has de-privileged so that the 'kvm_arm_pmu_available' static key can still be enabled by patching the hypervisor text. As it happens, both of these events hang off device_initcall() but the PMU consistently won the race until 7755cec63ade ("arm64: perf: Move PMUv3 driver to drivers/perf"). Since then, the host will fail to boot when pKVM is enabled: | hw perfevents: enabled with armv8_pmuv3_0 PMU driver, 7 counters available | kvm [1]: nVHE hyp BUG at: [] __kvm_nvhe_handle_host_mem_abort+0x270/0x284! | kvm [1]: Cannot dump pKVM nVHE stacktrace: !CONFIG_PROTECTED_NVHE_STACKTRACE | kvm [1]: Hyp Offset: 0xfffea41fbdf70000 | Kernel panic - not syncing: HYP panic: | PS:a00003c9 PC:0000dbe04b0c66e0 ESR:00000000f2000800 | FAR:fffffbfffddfcf00 HPFAR:00000000010b0bf0 PAR:0000000000000000 | VCPU:0000000000000000 | CPU: 2 PID: 1 Comm: swapper/0 Not tainted 6.3.0-rc7-00083-g0bce6746d154 #1 | Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015 | Call trace: | dump_backtrace+0xec/0x108 | show_stack+0x18/0x2c | dump_stack_lvl+0x50/0x68 | dump_stack+0x18/0x24 | panic+0x13c/0x33c | nvhe_hyp_panic_handler+0x10c/0x190 | aarch64_insn_patch_text_nosync+0x64/0xc8 | arch_jump_label_transform+0x4c/0x5c | __jump_label_update+0x84/0xfc | jump_label_update+0x100/0x134 | static_key_enable_cpuslocked+0x68/0xac | static_key_enable+0x20/0x34 | kvm_host_pmu_init+0x88/0xa4 | armpmu_register+0xf0/0xf4 | arm_pmu_acpi_probe+0x2ec/0x368 | armv8_pmu_driver_init+0x38/0x44 | do_one_initcall+0xcc/0x240 Fix the race properly by deferring the de-privilege step to device_initcall_sync(). This will also be needed in future when probing IOMMU devices and allows us to separate the pKVM de-privilege logic from the core hypervisor initialisation path. Cc: Oliver Upton Cc: Fuad Tabba Cc: Marc Zyngier Fixes: 7755cec63ade ("arm64: perf: Move PMUv3 driver to drivers/perf") Signed-off-by: Will Deacon Tested-by: Fuad Tabba Acked-by: Marc Zyngier --- Marc, Oliver -- in practice, this issue only crops with the patches moving the CPU PMU driver out into drivers/perf/ and so the arm64 for-next/core branch is broken. Please can I queue this in the arm64 tree for 6.4 with your Ack? Thanks. arch/arm64/kvm/arm.c | 45 ----------------------------------------- arch/arm64/kvm/pkvm.c | 47 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 47 insertions(+), 45 deletions(-) diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 3bd732eaf087..890f730bc3ab 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -16,7 +16,6 @@ #include #include #include -#include #include #include #include @@ -46,7 +45,6 @@ #include static enum kvm_mode kvm_mode = KVM_MODE_DEFAULT; -DEFINE_STATIC_KEY_FALSE(kvm_protected_mode_initialized); DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector); @@ -2105,41 +2103,6 @@ static int __init init_hyp_mode(void) return err; } -static void __init _kvm_host_prot_finalize(void *arg) -{ - int *err = arg; - - if (WARN_ON(kvm_call_hyp_nvhe(__pkvm_prot_finalize))) - WRITE_ONCE(*err, -EINVAL); -} - -static int __init pkvm_drop_host_privileges(void) -{ - int ret = 0; - - /* - * Flip the static key upfront as that may no longer be possible - * once the host stage 2 is installed. - */ - static_branch_enable(&kvm_protected_mode_initialized); - on_each_cpu(_kvm_host_prot_finalize, &ret, 1); - return ret; -} - -static int __init finalize_hyp_mode(void) -{ - if (!is_protected_kvm_enabled()) - return 0; - - /* - * Exclude HYP sections from kmemleak so that they don't get peeked - * at, which would end badly once inaccessible. - */ - kmemleak_free_part(__hyp_bss_start, __hyp_bss_end - __hyp_bss_start); - kmemleak_free_part_phys(hyp_mem_base, hyp_mem_size); - return pkvm_drop_host_privileges(); -} - struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr) { struct kvm_vcpu *vcpu; @@ -2257,14 +2220,6 @@ static __init int kvm_arm_init(void) if (err) goto out_hyp; - if (!in_hyp_mode) { - err = finalize_hyp_mode(); - if (err) { - kvm_err("Failed to finalize Hyp protection\n"); - goto out_subs; - } - } - if (is_protected_kvm_enabled()) { kvm_info("Protected nVHE mode initialized successfully\n"); } else if (in_hyp_mode) { diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c index cf56958b1492..6e9ece1ebbe7 100644 --- a/arch/arm64/kvm/pkvm.c +++ b/arch/arm64/kvm/pkvm.c @@ -4,6 +4,8 @@ * Author: Quentin Perret */ +#include +#include #include #include #include @@ -13,6 +15,8 @@ #include "hyp_constants.h" +DEFINE_STATIC_KEY_FALSE(kvm_protected_mode_initialized); + static struct memblock_region *hyp_memory = kvm_nvhe_sym(hyp_memory); static unsigned int *hyp_memblock_nr_ptr = &kvm_nvhe_sym(hyp_memblock_nr); @@ -213,3 +217,46 @@ int pkvm_init_host_vm(struct kvm *host_kvm) mutex_init(&host_kvm->lock); return 0; } + +static void __init _kvm_host_prot_finalize(void *arg) +{ + int *err = arg; + + if (WARN_ON(kvm_call_hyp_nvhe(__pkvm_prot_finalize))) + WRITE_ONCE(*err, -EINVAL); +} + +static int __init pkvm_drop_host_privileges(void) +{ + int ret = 0; + + /* + * Flip the static key upfront as that may no longer be possible + * once the host stage 2 is installed. + */ + static_branch_enable(&kvm_protected_mode_initialized); + on_each_cpu(_kvm_host_prot_finalize, &ret, 1); + return ret; +} + +static int __init finalize_pkvm(void) +{ + int ret; + + if (!is_protected_kvm_enabled()) + return 0; + + /* + * Exclude HYP sections from kmemleak so that they don't get peeked + * at, which would end badly once inaccessible. + */ + kmemleak_free_part(__hyp_bss_start, __hyp_bss_end - __hyp_bss_start); + kmemleak_free_part_phys(hyp_mem_base, hyp_mem_size); + + ret = pkvm_drop_host_privileges(); + if (ret) + pr_err("Failed to finalize Hyp protection: %d\n", ret); + + return ret; +} +device_initcall_sync(finalize_pkvm);