From patchwork Thu Oct 6 00:34:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 12999710 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7DCA6C4332F for ; Thu, 6 Oct 2022 00:34:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229913AbiJFAeq (ORCPT ); Wed, 5 Oct 2022 20:34:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229886AbiJFAeY (ORCPT ); Wed, 5 Oct 2022 20:34:24 -0400 Received: from mail-pg1-x549.google.com (mail-pg1-x549.google.com [IPv6:2607:f8b0:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B1B8868A9 for ; Wed, 5 Oct 2022 17:34:22 -0700 (PDT) Received: by mail-pg1-x549.google.com with SMTP id s15-20020a63524f000000b0043891d55a30so172543pgl.16 for ; Wed, 05 Oct 2022 17:34:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=9KMeIXPq6GpOVcN55NK7DLftKaRG2/H9/8QOpBzCftA=; b=mEbovaZUu6KW+QLA8E55+qeFjie4ez91koDXMg/9jrSIxWWEn7uEXQSfyV6u9Rbj0q au+eMV2cQU3MEP1qaqbhmLXZQ22xX+sXG6ruwTxeU1jSpEp6tgybSt375ZJjx+bepNLM ShKht/UF9CsHv4HlbDU1Rt5Aheu1FTSX309sP2UUTedYtoOrW+vfR9f+Rms2jv0qL311 xhlrOVJUHNxdYz4Uf6SXwcR5JfRoPwVhg+kAqr6R6aeYjuIwiPye2GNCzJ2FMX2W/GIu ZBZjpz3Kikj1neTh8F0SJ5mQd3pQSFV0yDiAcIjnkYV9DVRUgpC7CVc4TxECrfjAs5Jp /dpA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=9KMeIXPq6GpOVcN55NK7DLftKaRG2/H9/8QOpBzCftA=; b=lhm+Z24RWEE4Upyswr1XNSL7zTLYXRGQtNjxtdudnMsIDzNjm8f75xySeClcxzJbJb lTpClkvHdXBnZjfyxOdRWCaXmlkbiLx6he6/L/xRGJ6F/C/hrJUmWgW9NF5R9gCXjuoE 1FynZcfnkmx1q/z8DzBq06ojvRzsXh9+TZaKS4STZ9eqZqj4NDPvPX+3bG3zypqNi/Nu YIrMx25PuPiRKlkwRRAIgBwQUfVh0YXGnqmkhympHhpZNLsb4BzPAYVo+jqtAalYLT1w 7lgamvULdn02BrFiaqMcL8JhcYR16gIh3as1cPBs+k0x+JNDHFuTFGLwzNdGkkXN53o0 sCqA== X-Gm-Message-State: ACrzQf16FTjAmp5ZtUxS5QAijBLsP2U86SY0+cL5unmoI5Sg5GLMTkgz SrzDwOpHkJTcO8bcn/N/KzB/0//v6Zk= X-Google-Smtp-Source: AMsMyM45qnrI9G6azK6iw6bHSpADVc1CoVnhaNByhJReWqWjXc5QYOLtqbmuu2pzhK5ymOSC9YZe69vGWgs= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6a00:f0f:b0:562:3169:eba1 with SMTP id cr15-20020a056a000f0f00b005623169eba1mr2284230pfb.59.1665016461754; Wed, 05 Oct 2022 17:34:21 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 6 Oct 2022 00:34:07 +0000 In-Reply-To: <20221006003409.649993-1-seanjc@google.com> Mime-Version: 1.0 References: <20221006003409.649993-1-seanjc@google.com> X-Mailer: git-send-email 2.38.0.rc1.362.ged0d419d3c-goog Message-ID: <20221006003409.649993-6-seanjc@google.com> Subject: [PATCH v6 5/7] KVM: selftests: Make arm64's MMIO ucall multi-VM friendly From: Sean Christopherson To: Paolo Bonzini , Shuah Khan , Marc Zyngier , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Nathan Chancellor , Nick Desaulniers Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , Tom Rix , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, llvm@lists.linux.dev, Colton Lewis , Andrew Jones , Peter Gonda , Sean Christopherson Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Fix a mostly-theoretical bug where ARM's ucall MMIO setup could result in different VMs stomping on each other by cloberring the global pointer. Fix the most obvious issue by saving the MMIO gpa into the VM. A more subtle bug is that creating VMs in parallel (on multiple tasks) could result in a VM using the wrong address. Synchronizing a global to a guest effectively snapshots the value on a per-VM basis, i.e. the "global" is already prepped to work with multiple VMs, but setting the global in the host is not thread-safe. To fix that bug, add write_guest_global() to allow stuffing a VM's copy of a "global" without modifying the host value. Reviewed-by: Andrew Jones Tested-by: Peter Gonda Signed-off-by: Sean Christopherson --- .../selftests/kvm/include/kvm_util_base.h | 15 +++++++++++++++ .../testing/selftests/kvm/lib/aarch64/ucall.c | 19 ++++++++++++++----- 2 files changed, 29 insertions(+), 5 deletions(-) diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h index e42a09cd24a0..c14d531a942a 100644 --- a/tools/testing/selftests/kvm/include/kvm_util_base.h +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h @@ -16,6 +16,7 @@ #include #include "linux/rbtree.h" +#include #include @@ -81,6 +82,7 @@ struct kvm_vm { struct sparsebit *vpages_mapped; bool has_irqchip; bool pgd_created; + vm_paddr_t ucall_mmio_addr; vm_paddr_t pgd; vm_vaddr_t gdt; vm_vaddr_t tss; @@ -718,6 +720,19 @@ kvm_userspace_memory_region_find(struct kvm_vm *vm, uint64_t start, memcpy(&(g), _p, sizeof(g)); \ }) +/* + * Write a global value, but only in the VM's (guest's) domain. Primarily used + * for "globals" that hold per-VM values (VMs always duplicate code and global + * data into their own region of physical memory), but can be used anytime it's + * undesirable to change the host's copy of the global. + */ +#define write_guest_global(vm, g, val) ({ \ + typeof(g) *_p = addr_gva2hva(vm, (vm_vaddr_t)&(g)); \ + typeof(g) _val = val; \ + \ + memcpy(_p, &(_val), sizeof(g)); \ +}) + void assert_on_unhandled_exception(struct kvm_vcpu *vcpu); void vcpu_arch_dump(FILE *stream, struct kvm_vcpu *vcpu, diff --git a/tools/testing/selftests/kvm/lib/aarch64/ucall.c b/tools/testing/selftests/kvm/lib/aarch64/ucall.c index f02ae27c3e43..1c38bd260f90 100644 --- a/tools/testing/selftests/kvm/lib/aarch64/ucall.c +++ b/tools/testing/selftests/kvm/lib/aarch64/ucall.c @@ -6,20 +6,29 @@ */ #include "kvm_util.h" +/* + * ucall_exit_mmio_addr holds per-VM values (global data is duplicated by each + * VM), it must not be accessed from host code. + */ static vm_vaddr_t *ucall_exit_mmio_addr; +static void ucall_set_mmio_addr(struct kvm_vm *vm, vm_paddr_t mmio_gpa) +{ + vm->ucall_mmio_addr = mmio_gpa; + + write_guest_global(vm, ucall_exit_mmio_addr, (vm_vaddr_t *)mmio_gpa); +} + void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa) { virt_pg_map(vm, mmio_gpa, mmio_gpa); - ucall_exit_mmio_addr = (vm_vaddr_t *)mmio_gpa; - sync_global_to_guest(vm, ucall_exit_mmio_addr); + ucall_set_mmio_addr(vm, mmio_gpa); } void ucall_arch_uninit(struct kvm_vm *vm) { - ucall_exit_mmio_addr = 0; - sync_global_to_guest(vm, ucall_exit_mmio_addr); + ucall_set_mmio_addr(vm, (vm_paddr_t)NULL); } void ucall_arch_do_ucall(vm_vaddr_t uc) @@ -32,7 +41,7 @@ void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu) struct kvm_run *run = vcpu->run; if (run->exit_reason == KVM_EXIT_MMIO && - run->mmio.phys_addr == (uint64_t)ucall_exit_mmio_addr) { + run->mmio.phys_addr == vcpu->vm->ucall_mmio_addr) { vm_vaddr_t gva; TEST_ASSERT(run->mmio.is_write && run->mmio.len == 8,