From patchwork Fri Feb 25 03:34:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kalesh Singh X-Patchwork-Id: 12759616 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 C900AC433EF for ; Fri, 25 Feb 2022 03:45:18 +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:Cc:From:Subject:References:Mime-Version :Message-Id:In-Reply-To:Date:Reply-To:To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=qUelSbD1TGk3/GRjjgpiYujU48YRXcuQHiHHveE4hIA=; b=GRi49EeYOObnbT +g+IPWGj3+50MQQKxHoQ+r8XiPxKVcp4Lx0wEqd3rKbKT8vFlekCZ1N20kOraXI7+zm28h3siN7Z3 jHrE3hllF9JVMwmQv/a++NDrXZn9CJJi1ErJogbqtFt3aFU0owSXBdDLdjgzVtWUjQGiGixs+oBlW KcyZGU4si4uqNQ1U3Ba7ooz5UXTcI8JcIxB3pLlAAF1c+9Y1Amsu2cSrh9Rbx573bdlzVdoxkqYv0 moM8mUwAZbvu1kBr5v7h8MOKi3bR+7sMbQsXJjMvtJvzVfETHyDkvgTXg1P30Iu4Bevnk0KSN8uAz g5TC+xbg0WUo8uZ3SY3g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nNRWQ-0038PB-VQ; Fri, 25 Feb 2022 03:43:59 +0000 Received: from mail-yb1-xb4a.google.com ([2607:f8b0:4864:20::b4a]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nNRWM-0038NT-Vl for linux-arm-kernel@lists.infradead.org; Fri, 25 Feb 2022 03:43:56 +0000 Received: by mail-yb1-xb4a.google.com with SMTP id k10-20020a056902070a00b0062469b00335so1990894ybt.14 for ; Thu, 24 Feb 2022 19:43:54 -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=N53fsYbjdomZEqC08ZX2aLHLeu/DgUziJYRqEwUtI1A=; b=RDsCf9B/tbqpBWDVVLA0Uni/cUxBssEL82brdpQDflFscrjWeDp/IrFbmB2lXkwnOT +aBRWNfkxrYjNC06MXJX+XbipoXeQdIouEFph61JxnLy+dAT8wBgGgTRmpGb6ZeE08OW 7pwzwrlXeD3rOPlWuIroN5SUiUVJPqFsleOthEEoxub28NOvTT+YyUVHv2PlkCalpcgo qgwxVpdwC96gSO2gBGYZYG9DZwu2zh03MCxlgz5iq6nL9h/OBROE4CheyUhRwlryYluZ Pe15eTYZFhbKKqb8Vi5+4TLV3djTewGaBaZDmTc1qVLOTEnaHckwbPlSu9/2sm80a6Zj uLlg== 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=N53fsYbjdomZEqC08ZX2aLHLeu/DgUziJYRqEwUtI1A=; b=CwvcR6c2n2iRXGSUYXaQanb965YDp9IyZJX5Jp6TJHHX4GsWWvMoFai+7emvT5eKFy srWS0Ui6GEVA2D5HmEJWmND45KSV/B9+Q1z88AaAUPR7SFaQU7Xuc5UhdNkRQhPyC1UP 1Vfh+GP/wIe7ucWnzEpin8pQi8APkfU7RThxk6YHqcpS4YdwxQm6FNOPQ7MKkGQN4SJT m7mDjh/6RF0qJq+Kp5lCfb4wIBsctuIDcTlwCQnjsEX1V+/iCeOT4mpRv4Yvlg99T6uK 9CaHA6/3MPemXb2yuynqQP8uX87QPazKdZUEQbHh0FBEL0XH+qI03gMVZyDpgjh0C18F mD3A== X-Gm-Message-State: AOAM5321hW98aI0HIeUlaAtO336PZy/6EDt2lTsXbkL3ZqHZl870t2F7 kdOkuQDY6zezq2nkH4nq599TSrreXN93lLYRTw== X-Google-Smtp-Source: ABdhPJyXz9CYv8vpYP/3Z7ESWeXMCWY52bhCF65m+jCDLtu1xmRA3zZ3JjZrJQKEzrQefdbm9ToCdQ84n4fL6vpCfQ== X-Received: from kaleshsingh.mtv.corp.google.com ([2620:15c:211:200:3a50:90b2:e6a2:9060]) (user=kaleshsingh job=sendgmr) by 2002:a25:df51:0:b0:624:5c91:8e76 with SMTP id w78-20020a25df51000000b006245c918e76mr5460126ybg.337.1645760633363; Thu, 24 Feb 2022 19:43:53 -0800 (PST) Date: Thu, 24 Feb 2022 19:34:50 -0800 In-Reply-To: <20220225033548.1912117-1-kaleshsingh@google.com> Message-Id: <20220225033548.1912117-6-kaleshsingh@google.com> Mime-Version: 1.0 References: <20220225033548.1912117-1-kaleshsingh@google.com> X-Mailer: git-send-email 2.35.1.574.g5d30c73bfb-goog Subject: [PATCH v4 5/8] 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 , James Morse , Alexandru Elisei , Suzuki K Poulose , Catalin Marinas , Mark Rutland , Mark Brown , Masami Hiramatsu , Peter Collingbourne , "Madhavan T. Venkataraman" , Andrew Scull , Paolo Bonzini , Andrew Jones , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220224_194355_053972_ED056344 X-CRM114-Status: GOOD ( 14.34 ) 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 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 --- Changes in v3: - Remove test_sp_overflow macro, per Mark - Add asmlinkage attribute for hyp_panic, hyp_panic_bad_stack, per Ard arch/arm64/kvm/hyp/nvhe/host.S | 24 ++++++++++++++++++++++++ arch/arm64/kvm/hyp/nvhe/switch.c | 7 ++++++- 2 files changed, 30 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S index 3d613e721a75..749961bfa5ba 100644 --- a/arch/arm64/kvm/hyp/nvhe/host.S +++ b/arch/arm64/kvm/hyp/nvhe/host.S @@ -153,6 +153,18 @@ SYM_FUNC_END(__host_hvc) .macro invalid_host_el2_vect .align 7 + + /* + * Test whether the SP has overflowed, without corrupting a GPR. + * nVHE hypervisor stacks are aligned so that SP & (1 << PAGE_SHIFT) + * should always be zero. + */ + add sp, sp, x0 // sp' = sp + x0 + sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp + tbnz x0, #PAGE_SHIFT, .L__hyp_sp_overflow\@ + sub x0, sp, x0 // x0'' = sp' - x0' = (sp + x0) - sp = x0 + sub sp, sp, x0 // sp'' = sp' - x0 = (sp + x0) - x0 = sp + /* If a guest is loaded, panic out of it. */ stp x0, x1, [sp, #-16]! get_loaded_vcpu x0, x1 @@ -165,6 +177,18 @@ 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..703a5d3f611b 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -347,7 +347,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu) return exit_code; } -void __noreturn hyp_panic(void) +asmlinkage void __noreturn hyp_panic(void) { u64 spsr = read_sysreg_el2(SYS_SPSR); u64 elr = read_sysreg_el2(SYS_ELR); @@ -369,6 +369,11 @@ void __noreturn hyp_panic(void) unreachable(); } +asmlinkage void __noreturn hyp_panic_bad_stack(void) +{ + hyp_panic(); +} + asmlinkage void kvm_unexpected_el2_exception(void) { return __kvm_unexpected_el2_exception();