From mboxrd@z Thu Jan 1 00:00:00 1970 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 67181C433F5 for ; Tue, 22 Feb 2022 16:59:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234446AbiBVQ77 (ORCPT ); Tue, 22 Feb 2022 11:59:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233343AbiBVQ75 (ORCPT ); Tue, 22 Feb 2022 11:59:57 -0500 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67CE116C4D1 for ; Tue, 22 Feb 2022 08:59:32 -0800 (PST) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-2d6994a6942so144242377b3.17 for ; Tue, 22 Feb 2022 08:59:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:cc; bh=kA1uHTXTZgvCDEwUv0Venj02VbjFVl5MyBDxltrhOyc=; b=NP6fnietNid07WODom2crvgVApuYNwyBc+vaQeT9ELb0Wby0y027V1WoutortBDdER 6VKH2m5g/hhqE8jP+GV8Z52SXKndZFpGpqKGnvqTJ6saOgO9yiXq/Sl8KOE48ShXSFrf Yd/GQs7iTARZWcbcAbs2DZcziHvlIf4ws8th2T86PRoxGLRCAo79SHT5a0UzBseydVww c/kdTBUTDmKW4WhBmbRdCfs4Sm1ZyK65IyLMvKPqQFMBa2uiSRCXXe8ja7vMgkYdHVOd FDQ7AFIgQCuxZCe7VWKGtZS0vLPpQ4mLhJFEH4IE0gr/JO65ZVTSGIb2gzhuMTjBEe1w 9t+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:cc; bh=kA1uHTXTZgvCDEwUv0Venj02VbjFVl5MyBDxltrhOyc=; b=eDjOWfIo2bmmatAkxeRJT9A2HVV0AO7Djm8cCgheIbzbt7TOZVPEi9XYBJm6REpUgt kbrMz6/RJHDxAX6fswwzKSRv95B4Z35qH9RmNQqai9TZhxap59fs1ncu0OXFoZfOZS/o dFC7RbioUBJoBACrpXTklOzcRsgT4pVEPO6kW5628WREQOZH/MBP6gtwdx1DT5nT9HPn RepUzZPR7PN2AKd4AMuyW3dU7leenhgpcN4/T1Q0cM1AJQBN6GOB/Rce9141C3YDK4ts S1nXg6PvGgOdZhGGCfvSPHvew4m5toCtdGttMGMq1QM5wvVwuMwWhd2EmDZwgxqiJgrI i9sA== X-Gm-Message-State: AOAM533x02fkjgpRA55wHW0ED00fQtHyveRM1S/kmK1RHqSb6Ue0uku2 D8/h8lNid62yp1dve0BbwMqO5BaWOw2ADf9YTQ== X-Google-Smtp-Source: ABdhPJw2THd1z2iAbfih7pFjkHmBG5AlQKbmEqgBiWlGmwrM/dGUOKWBoivdDJ4o6t47SOdmT8K0alB2LRMYcbGgbA== X-Received: from kaleshsingh.mtv.corp.google.com ([2620:15c:211:200:5db7:1235:b3dd:cfcb]) (user=kaleshsingh job=sendgmr) by 2002:a81:138a:0:b0:2d6:b391:90cd with SMTP id 132-20020a81138a000000b002d6b39190cdmr23404107ywt.480.1645549171601; Tue, 22 Feb 2022 08:59:31 -0800 (PST) Date: Tue, 22 Feb 2022 08:51:07 -0800 In-Reply-To: <20220222165212.2005066-1-kaleshsingh@google.com> Message-Id: <20220222165212.2005066-7-kaleshsingh@google.com> Mime-Version: 1.0 References: <20220222165212.2005066-1-kaleshsingh@google.com> X-Mailer: git-send-email 2.35.1.473.g83b2b277ed-goog Subject: [PATCH v2 6/9] KVM: arm64: Detect and handle hypervisor stack overflows From: Kalesh Singh Cc: will@kernel.org, maz@kernel.org, qperret@google.com, tabba@google.com, surenb@google.com, kernel-team@android.com, Kalesh Singh , Catalin Marinas , James Morse , Alexandru Elisei , Suzuki K Poulose , Ard Biesheuvel , Mark Rutland , Pasha Tatashin , Joey Gouly , Peter Collingbourne , Andrew Scull , Paolo Bonzini , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu Content-Type: text/plain; charset="UTF-8" To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The hypervisor stacks (for both nVHE Hyp mode and nVHE protected mode) are aligned to twice their size (PAGE_SIZE), meaning that any valid stack address has PAGE_SHIFT bit as 0. This allows us to conveniently check for overflow in the exception entry without corrupting any GPRs. We won't recover from a stack overflow so panic the hypervisor. Signed-off-by: Kalesh Singh --- arch/arm64/kvm/hyp/nvhe/host.S | 16 ++++++++++++++++ arch/arm64/kvm/hyp/nvhe/switch.c | 5 +++++ 2 files changed, 21 insertions(+) diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S index 3d613e721a75..78e4b612ac06 100644 --- a/arch/arm64/kvm/hyp/nvhe/host.S +++ b/arch/arm64/kvm/hyp/nvhe/host.S @@ -153,6 +153,10 @@ SYM_FUNC_END(__host_hvc) .macro invalid_host_el2_vect .align 7 + + /* Test stack overflow without corrupting GPRs */ + test_sp_overflow PAGE_SHIFT, .L__hyp_sp_overflow\@ + /* If a guest is loaded, panic out of it. */ stp x0, x1, [sp, #-16]! get_loaded_vcpu x0, x1 @@ -165,6 +169,18 @@ SYM_FUNC_END(__host_hvc) * been partially clobbered by __host_enter. */ b hyp_panic + +.L__hyp_sp_overflow\@: + /* + * Reset SP to the top of the stack, to allow handling the hyp_panic. + * This corrupts the stack but is ok, since we won't be attempting + * any unwinding here. + */ + ldr_this_cpu x0, kvm_init_params + NVHE_INIT_STACK_HYP_VA, x1 + mov sp, x0 + + bl hyp_panic_bad_stack + ASM_BUG() .endm .macro invalid_host_el1_vect diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c index 6410d21d8695..5a2e1ab79913 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -369,6 +369,11 @@ void __noreturn hyp_panic(void) unreachable(); } +void __noreturn hyp_panic_bad_stack(void) +{ + hyp_panic(); +} + asmlinkage void kvm_unexpected_el2_exception(void) { return __kvm_unexpected_el2_exception(); -- 2.35.1.473.g83b2b277ed-goog