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 3C2D6C433F5 for ; Thu, 24 Feb 2022 05:20:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230136AbiBXFUv (ORCPT ); Thu, 24 Feb 2022 00:20:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229703AbiBXFUt (ORCPT ); Thu, 24 Feb 2022 00:20:49 -0500 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B16E17F69F for ; Wed, 23 Feb 2022 21:20:20 -0800 (PST) Received: by mail-yb1-xb49.google.com with SMTP id a19-20020a25ca13000000b0061db44646b3so943722ybg.2 for ; Wed, 23 Feb 2022 21:20:20 -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=H4Z1lUqUeabFhmJD3t8xVbX28HOrFIYN1Agzn114BGo=; b=LsQ97pcohFsj9RlBvIOR/HjRRTmpxuoxoVutPu6Mz8f8Qc8IiLUdOvgGwYWo6PkPqP edGd3S6spZfR1eG7lKcxxDMoY93t5dZyarnvaxqB/e8uaJHBjjHxpPojSAfvmbE5SA+q yH5/xwTQQ1ApMBlT4llh7MhcqVVpsUfgYdJ1iKJ6oqJz2HRvD5USeQ38eCXddXx5ogBv kE/jZINSl2wgXKpy0cIapbKMmmLn1hDj7jvYWPvUDNUUSNXkYBs9l0teLhdyiRhTAVOk Py2ZxE/qmDVu81csLNOLFCwMGUyw/uXDQMhoEajwvjW82rbKO4U8DeRxLYT0WkngZ4FK 0i+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=H4Z1lUqUeabFhmJD3t8xVbX28HOrFIYN1Agzn114BGo=; b=Kk836Pr9nDrMk4CN2Z3UgJrVd2wzbzybrrox53ot+RklZHRUsk4YkYOKFj3MO8BqwM 7aNR3j0TBZn1OaA2sre/ndUuxU2GIuVW476AvTEibl2yjhjv8YvojVPTBSLLpBjK0DB4 d9jIbfx4FMaJPH8UCvjSLFmrxzJyeyGKbiE0ZrbMIF1Jro0423n4yhVnFn7hFnXUu21x INM+RMKGREgDxb/AFI1Mec880fmUQr0vSjMBJ2DHdgqswB9HN7MIWKEmBiW7w1ML84pA UTdjOi0L9zXW1sq1mWLkxS1cS5gGaBXYcSF8dL2u6Bhr2EfzG9VA1YrWj1aUt+nxc3qw s+Yg== X-Gm-Message-State: AOAM530L78e8wAKpBP4x7knh3fix42+atMdVb+q3NtFzQhlA84QnuXb1 sWHbQ8xO82bIizb+F+jbqnFrPIZ/SMNuKfSlpQ== X-Google-Smtp-Source: ABdhPJz5Qiz49suSJpWhdDGBZ/Par4c6tTpWzRj6zIuxEJHxtLIJ4WzGG0ZrNy9JUdjCvZK71gx48FILjtMxJXC9CQ== X-Received: from kaleshsingh.mtv.corp.google.com ([2620:15c:211:200:415c:9be0:c461:440a]) (user=kaleshsingh job=sendgmr) by 2002:a25:374d:0:b0:611:a6c1:b948 with SMTP id e74-20020a25374d000000b00611a6c1b948mr1007735yba.21.1645680019488; Wed, 23 Feb 2022 21:20:19 -0800 (PST) Date: Wed, 23 Feb 2022 21:13:40 -0800 In-Reply-To: <20220224051439.640768-1-kaleshsingh@google.com> Message-Id: <20220224051439.640768-6-kaleshsingh@google.com> Mime-Version: 1.0 References: <20220224051439.640768-1-kaleshsingh@google.com> X-Mailer: git-send-email 2.35.1.473.g83b2b277ed-goog Subject: [PATCH v3 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 Walbran , Andrew Scull , Zenghui Yu , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org 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 --- 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(); -- 2.35.1.473.g83b2b277ed-goog