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 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 AACCAD116F5 for ; Sun, 30 Nov 2025 13:12:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: References:In-Reply-To:Subject:Cc:To:From:Message-ID:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=YjdNfVrLumjJxTfeAweFuFRdWxPCZgQuIRJ8jsw9HQI=; b=3/n8UawO2sNd0rvcyunZKwFcFN FZloNKcD5D4hMwzZ7GI6o+rAVv6bsyVyabSUQY4vjgw5fcHplu71I0sLnTqHWQZEWSxAxM7vEUWav 7inntBOqyPQWDFgrYdUjEx2J0ODO0Sh8oU7fCziVOSYfCh4g7JO9FciALX5S3tP60IbipFuqayOgE ylKuktxYgHMwev9DjKDgKML2Skodp1HzBrQOBnr/oLQovGrL2Q4cJ+THzphzxt0Ujyw+e4RgMJ+Rm PC4r4q7DzOV3sMu0Du8wQeOTSi8/REEjNkzEpFjMuy1Be6KyOe3I+J6FIhTJY5DPXP9iZIng3XXNw 6YrdINeg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vPhDj-00000002K0L-3sfg; Sun, 30 Nov 2025 13:12:07 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vPhDh-00000002Jzv-3O39 for linux-arm-kernel@lists.infradead.org; Sun, 30 Nov 2025 13:12:06 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id CBE004069F; Sun, 30 Nov 2025 13:12:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB576C4CEF8; Sun, 30 Nov 2025 13:12:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764508320; bh=ZgigReiyWWOX6rMHBjUflJ+pjs/WLbBCc/fUEa2OSqo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=u/IIDObnB/o6BIvA+3pZF1namXu63e4WWJGu55y/fK3RWVRsmkvXXQHnRL5N8W8T7 vI0HZTp7p4WUSLAf9v932gw2wxRT7UOYh78J0l/AV6TdauFHRI5fpXYakf488Ro4eD ytVD5U1vO+DHglHe4U0hfp8nHE1uTnNxo8DiZAtTYQlkMibOE6Mg5Y4m3s6XwhVdxj RGi/4GiNCnKLqQ9idc+olF/x0L9s+ntolRC8EqjIqKiboA8c98gLzi4WfZCClX7x9C Ga90ZuAob1FhPaw8w5156zW/VI406WcnouFxGDw0SFZGbjbBvfO/LhlB+86qgYArGH HfWXesCw8+fMw== Received: from sofa.misterjones.org ([185.219.108.64] helo=lobster-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1vPhDa-00000009PcT-1OIK; Sun, 30 Nov 2025 13:11:58 +0000 Date: Sun, 30 Nov 2025 13:11:57 +0000 Message-ID: <87a503fyw2.wl-maz@kernel.org> From: Marc Zyngier To: Alexandru Elisei Cc: oliver.upton@linux.dev, joey.gouly@arm.com, yuzenghui@huawei.com, suzuki.poulose@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev Subject: Re: [PATCH 0/4] KVM: arm64: nv: HAF fixes In-Reply-To: <20251128100946.74210-1-alexandru.elisei@arm.com> References: <20251128100946.74210-1-alexandru.elisei@arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: alexandru.elisei@arm.com, oliver.upton@linux.dev, joey.gouly@arm.com, yuzenghui@huawei.com, suzuki.poulose@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251130_051205_905288_2C876710 X-CRM114-Status: GOOD ( 28.18 ) 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 On Fri, 28 Nov 2025 10:09:42 +0000, Alexandru Elisei wrote: > > Based on kvmarm's next branch. > > HAF support for the software translation table walker was merged while I > was in the process of reading the patches, so instead of comments I have > these few fixes. > > One thing I didn't touch is this sequence in hyp_set_prot_attr(): > > if (prot & KVM_PGTABLE_PROT_X) { > /* don't set the XN bit */ > } else { > attr |= KVM_PTE_LEAF_ATTR_HI_S1_XN; > } > > If the caller is executing in nVHE mode, the translation regime is EL2, > which has only PrivExecute permission. Since KVM_PGTABLE_PROT_X is now the > union of PrivExecute and UnprivExecute, if the caller requests only the > UnprivExecute permission, but no PrivExecute permission, the function does > not return an error code and sets the PrivExecute permission. I don't think this is a huge problem *right now*, as long as we don't have anything that looks like "hvhe hypervisor userspace" (yes, I proposed that a while ago, and haven't completely dropped the idea). But at the same time, the page-table code should probably be built to the architecture and not to the use cases. But it also outlines a rather bad bug in the hVHE case, where we set the UXN bit instead of the PXN bit... What I have in mind is something like this, untested. Thoughts? M. diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index d57c12f074a40..48305118ba3c5 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -88,6 +88,8 @@ typedef u64 kvm_pte_t; #define KVM_PTE_LEAF_ATTR_HI_SW GENMASK(58, 55) #define KVM_PTE_LEAF_ATTR_HI_S1_XN BIT(54) +#define KVM_PTE_LEAF_ATTR_HI_S1_UXN BIT(54) +#define KVM_PTE_LEAF_ATTR_HI_S1_PXN BIT(53) #define KVM_PTE_LEAF_ATTR_HI_S2_XN GENMASK(54, 53) diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index e0bd6a0172729..cbf9b6b58e284 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -330,6 +330,11 @@ struct hyp_map_data { kvm_pte_t attr; }; +static bool el2_nvhe(void) +{ + return !has_vhe() && !cpus_have_final_cap(ARM64_KVM_PROTECTED_MODE); +} + static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep) { bool device = prot & KVM_PGTABLE_PROT_DEVICE; @@ -342,6 +347,9 @@ static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep) if (!(prot & KVM_PGTABLE_PROT_R)) return -EINVAL; + if (el2_nvhe()) + prot &= ~KVM_PGTABLE_PROT_UX; + if (prot & KVM_PGTABLE_PROT_X) { if (prot & KVM_PGTABLE_PROT_W) return -EINVAL; @@ -351,8 +359,16 @@ static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep) if (system_supports_bti_kernel()) attr |= KVM_PTE_LEAF_ATTR_HI_S1_GP; + } + + if (el2_nvhe()) { + if (!(prot & KVM_PGTABLE_PROT_PX)) + attr |= KVM_PTE_LEAF_ATTR_HI_S1_XN; } else { - attr |= KVM_PTE_LEAF_ATTR_HI_S1_XN; + if (!(prot & KVM_PGTABLE_PROT_PX)) + attr |= KVM_PTE_LEAF_ATTR_HI_S1_PXN; + if (!(prot & KVM_PGTABLE_PROT_UX)) + attr |= KVM_PTE_LEAF_ATTR_HI_S1_UXN; } attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S1_AP, ap); @@ -373,8 +389,15 @@ enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte) if (!kvm_pte_valid(pte)) return prot; - if (!(pte & KVM_PTE_LEAF_ATTR_HI_S1_XN)) - prot |= KVM_PGTABLE_PROT_X; + if (el2_nvhe()) { + if (!(pte & KVM_PTE_LEAF_ATTR_HI_S1_XN)) + prot |= KVM_PGTABLE_PROT_PX; + } else { + if (!(pte & KVM_PTE_LEAF_ATTR_HI_S1_PXN)) + prot |= KVM_PGTABLE_PROT_PX; + if (!(pte & KVM_PTE_LEAF_ATTR_HI_S1_UXN)) + prot |= KVM_PGTABLE_PROT_UX; + } ap = FIELD_GET(KVM_PTE_LEAF_ATTR_LO_S1_AP, pte); if (ap == KVM_PTE_LEAF_ATTR_LO_S1_AP_RO) -- Jazz isn't dead. It just smells funny.