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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 17D97C433E1 for ; Thu, 4 Jun 2020 13:34:14 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id C2D42207F7 for ; Thu, 4 Jun 2020 13:34:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="UCGPpRD9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C2D42207F7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 6680A4B357; Thu, 4 Jun 2020 09:34:13 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@kernel.org Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 1MfRSZBmIt7D; Thu, 4 Jun 2020 09:34:10 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 69BA14B378; Thu, 4 Jun 2020 09:34:09 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B8D5C4B2FE for ; Thu, 4 Jun 2020 09:34:08 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JZVmE7wrS7n4 for ; Thu, 4 Jun 2020 09:34:07 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id A77334B327 for ; Thu, 4 Jun 2020 09:34:07 -0400 (EDT) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DAD8F20829; Thu, 4 Jun 2020 13:34:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591277647; bh=rotJuRrjsUR85tXo2BdW5+A/L5Ugu4nDYunoj5XseZ4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UCGPpRD9IJ9+GPQ3TWSKTU05OHcM/VphXHokwWzbhrdpLFx/eDNRYwqji0n/HGzVV cMjCXN35g+TBwjZkQS/5sIya4Vp88R2C6w6htT97ukxGsKKmGjhQTipyHOHCIqkaQh pKPoUb5LNgL6imf5v3AJpUNMyapbYKQ0Erphzs/o= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jgq0T-000G3O-Er; Thu, 04 Jun 2020 14:34:05 +0100 From: Marc Zyngier To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: [PATCH 3/3] KVM: arm64: Enforce PtrAuth being disabled if not advertized Date: Thu, 4 Jun 2020 14:33:54 +0100 Message-Id: <20200604133354.1279412-4-maz@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200604133354.1279412-1-maz@kernel.org> References: <20200604133354.1279412-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: kernel-team@android.com, Catalin Marinas , Will Deacon X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Even if we don't expose PtrAuth to a guest, the guest can still write to its SCTIRLE_1 register and set the En{I,D}{A,B} bits and execute PtrAuth instructions from the NOP space. This has the effect of trapping to EL2, and we currently inject an UNDEF. This is definitely the wrong thing to do, as the architecture says that these instructions should behave as NOPs. Instead, we can simply reset the offending SCTLR_EL1 bits to zero, and resume the guest. It can still observe the SCTLR bits being set and then being cleared by magic, but that's much better than delivering an unexpected extension. Signed-off-by: Marc Zyngier --- arch/arm64/kvm/handle_exit.c | 12 ------------ arch/arm64/kvm/hyp/switch.c | 18 ++++++++++++++++-- 2 files changed, 16 insertions(+), 14 deletions(-) diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index 5a02d4c90559..98d8adf6f865 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -162,17 +162,6 @@ static int handle_sve(struct kvm_vcpu *vcpu, struct kvm_run *run) return 1; } -/* - * Guest usage of a ptrauth instruction (which the guest EL1 did not turn into - * a NOP). If we get here, it is that we didn't fixup ptrauth on exit, and all - * that we can do is give the guest an UNDEF. - */ -static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu, struct kvm_run *run) -{ - kvm_inject_undefined(vcpu); - return 1; -} - static exit_handle_fn arm_exit_handlers[] = { [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec, [ESR_ELx_EC_WFx] = kvm_handle_wfx, @@ -195,7 +184,6 @@ static exit_handle_fn arm_exit_handlers[] = { [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug, [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd, - [ESR_ELx_EC_PAC] = kvm_handle_ptrauth, }; static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c index 2a50b3771c3b..fc09c3dfa466 100644 --- a/arch/arm64/kvm/hyp/switch.c +++ b/arch/arm64/kvm/hyp/switch.c @@ -503,8 +503,22 @@ static bool __hyp_text __hyp_handle_ptrauth(struct kvm_vcpu *vcpu) struct kvm_cpu_context *ctxt; u64 val; - if (!vcpu_has_ptrauth(vcpu)) - return false; + if (!vcpu_has_ptrauth(vcpu)) { + if (ec != ESR_ELx_EC_PAC) + return false; + + /* + * Interesting situation: the guest has enabled PtrAuth, + * despite KVM not advertising it. Fix SCTLR_El1 on behalf + * of the guest (the bits should behave as RES0 anyway). + */ + val = read_sysreg_el1(SYS_SCTLR); + val &= ~(SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | + SCTLR_ELx_ENDA | SCTLR_ELx_ENDB); + write_sysreg_el1(val, SYS_SCTLR); + + return true; + } switch (ec) { case ESR_ELx_EC_PAC: -- 2.26.2 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm