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 5999DF33A78 for ; Thu, 5 Mar 2026 14:45:52 +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-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=PXONJEKI+JMJd6aqPxYy0gCDepSXpk8I9hJZx5c03no=; b=hxnm69Iy2c+Txijuf2DWaojJ0q SDfJsCGJs73kxSvLuW/zuHAUxXnNFUkRftMob1cKAaxSsqD7XChZk6dW1LDYcY62fGk+mcx5PIp96 Z3uCfNYuGao/oq7jwd6ctX0dvUveFYGDf+bxSvOrSBI3efAiOhujyYbFKgR1V+qFUaGKa+FCA1FK9 hvGdJl1kguJTHoDJerMauqAVPBZtqgOZlbPFEMFDb0t1jGr6YzUvALUW3L0mu/7aifji8QGh8PQP9 YbCsnWvvLvrurlQCWi19bbv1vTY1DKT2z8YAThW/3kIDS0PO4s2VUUhyCKandHytHcbIH4YuNkMEw s56Cbcxg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vy9xQ-000000022Xm-1w4K; Thu, 05 Mar 2026 14:45:44 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vy9xO-000000022Ug-1DxZ for linux-arm-kernel@lists.infradead.org; Thu, 05 Mar 2026 14:45:42 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 56BE561854; Thu, 5 Mar 2026 14:45:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D239C2BC9E; Thu, 5 Mar 2026 14:45:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772721941; bh=AKNRP/YGBrx3P2RGsIR6JKzJ/ATDrTA/YgEov5g1Gz8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Z82IVU7FaFfLSSsmruvYtEBii//t1Z1PeSOWaBD5/LdGgBwLqQU0/fu7h10nQucOB T6qdyb6uHmKJUIJVDRQE3oiYDhf/yc+NMykY/9KAp4tRzUSLtp7Yj91Bt15TI6tZbd PkUb18jTMmxgzUnodyXb66/kPncST8H2Z9s1mP327hqLpuPJBnNzzhwdTg9pDzNMBC IZcc2Ea5r78uapxseg4VNvFiKFqSh3SP1xWfUJNnJVXxHX6qVr3j48VChT8ocstq47 yqsFAHx7JYhVS85/AIEM/aM1n91KFAeusvTom9xWiUll1IMvIBzvwTDoR05CIo7FOB q4oNgr+sh9abw== From: Will Deacon To: kvmarm@lists.linux.dev Cc: linux-arm-kernel@lists.infradead.org, Will Deacon , Marc Zyngier , Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Quentin Perret , Fuad Tabba , Vincent Donnefort , Mostafa Saleh , Alexandru Elisei Subject: [PATCH v3 26/36] KVM: arm64: Return -EFAULT from VCPU_RUN on access to a poisoned pte Date: Thu, 5 Mar 2026 14:43:39 +0000 Message-ID: <20260305144351.17071-27-will@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260305144351.17071-1-will@kernel.org> References: <20260305144351.17071-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 If a protected vCPU faults on an IPA which appears to be mapped, query the hypervisor to determine whether or not the faulting pte has been poisoned by a forceful reclaim. If the pte has been poisoned, return -EFAULT back to userspace rather than retrying the instruction forever. Signed-off-by: Will Deacon --- arch/arm64/include/asm/kvm_asm.h | 1 + arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 1 + arch/arm64/kvm/hyp/nvhe/hyp-main.c | 10 +++++ arch/arm64/kvm/hyp/nvhe/mem_protect.c | 43 +++++++++++++++++++ arch/arm64/kvm/pkvm.c | 9 ++-- 5 files changed, 61 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index 04a230e906a7..6c79f7504d80 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -90,6 +90,7 @@ enum __kvm_host_smccc_func { __KVM_HOST_SMCCC_FUNC___pkvm_unreserve_vm, __KVM_HOST_SMCCC_FUNC___pkvm_init_vm, __KVM_HOST_SMCCC_FUNC___pkvm_init_vcpu, + __KVM_HOST_SMCCC_FUNC___pkvm_vcpu_in_poison_fault, __KVM_HOST_SMCCC_FUNC___pkvm_force_reclaim_guest_page, __KVM_HOST_SMCCC_FUNC___pkvm_reclaim_dying_guest_page, __KVM_HOST_SMCCC_FUNC___pkvm_start_teardown_vm, diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h index f27b037abaf3..5e6cdafcdd69 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h @@ -41,6 +41,7 @@ int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages); int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages); int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages); int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu); +int __pkvm_vcpu_in_poison_fault(struct pkvm_hyp_vcpu *hyp_vcpu); int __pkvm_host_force_reclaim_page_guest(phys_addr_t phys); int __pkvm_host_reclaim_page_guest(u64 gfn, struct pkvm_hyp_vm *vm); int __pkvm_host_share_guest(u64 pfn, u64 gfn, u64 nr_pages, struct pkvm_hyp_vcpu *vcpu, diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index 456c83207717..90e3b14fe287 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -573,6 +573,15 @@ static void handle___pkvm_init_vcpu(struct kvm_cpu_context *host_ctxt) cpu_reg(host_ctxt, 1) = __pkvm_init_vcpu(handle, host_vcpu, vcpu_hva); } +static void handle___pkvm_vcpu_in_poison_fault(struct kvm_cpu_context *host_ctxt) +{ + int ret; + struct pkvm_hyp_vcpu *hyp_vcpu = pkvm_get_loaded_hyp_vcpu(); + + ret = hyp_vcpu ? __pkvm_vcpu_in_poison_fault(hyp_vcpu) : -EINVAL; + cpu_reg(host_ctxt, 1) = ret; +} + static void handle___pkvm_force_reclaim_guest_page(struct kvm_cpu_context *host_ctxt) { DECLARE_REG(phys_addr_t, phys, host_ctxt, 1); @@ -641,6 +650,7 @@ static const hcall_t host_hcall[] = { HANDLE_FUNC(__pkvm_unreserve_vm), HANDLE_FUNC(__pkvm_init_vm), HANDLE_FUNC(__pkvm_init_vcpu), + HANDLE_FUNC(__pkvm_vcpu_in_poison_fault), HANDLE_FUNC(__pkvm_force_reclaim_guest_page), HANDLE_FUNC(__pkvm_reclaim_dying_guest_page), HANDLE_FUNC(__pkvm_start_teardown_vm), diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index 4ff31947579b..7f705f662c40 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -890,6 +890,49 @@ static int get_valid_guest_pte(struct pkvm_hyp_vm *vm, u64 ipa, kvm_pte_t *ptep, return 0; } +int __pkvm_vcpu_in_poison_fault(struct pkvm_hyp_vcpu *hyp_vcpu) +{ + struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(hyp_vcpu); + kvm_pte_t pte; + s8 level; + u64 ipa; + int ret; + + switch (kvm_vcpu_trap_get_class(&hyp_vcpu->vcpu)) { + case ESR_ELx_EC_DABT_LOW: + case ESR_ELx_EC_IABT_LOW: + if (kvm_vcpu_trap_is_translation_fault(&hyp_vcpu->vcpu)) + break; + fallthrough; + default: + return -EINVAL; + } + + /* + * The host has the faulting IPA when it calls us from the guest + * fault handler but we retrieve it ourselves from the FAR so as + * to avoid exposing an "oracle" that could reveal data access + * patterns of the guest after initial donation of its pages. + */ + ipa = kvm_vcpu_get_fault_ipa(&hyp_vcpu->vcpu); + ipa |= kvm_vcpu_get_hfar(&hyp_vcpu->vcpu) & GENMASK(11, 0); + + guest_lock_component(vm); + ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level); + if (ret) + goto unlock; + + if (level != KVM_PGTABLE_LAST_LEVEL) { + ret = -EINVAL; + goto unlock; + } + + ret = guest_pte_is_poisoned(pte); +unlock: + guest_unlock_component(vm); + return ret; +} + int __pkvm_host_share_hyp(u64 pfn) { u64 phys = hyp_pfn_to_phys(pfn); diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c index 32294bd21dde..da0a45dab203 100644 --- a/arch/arm64/kvm/pkvm.c +++ b/arch/arm64/kvm/pkvm.c @@ -417,10 +417,13 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size, return -EINVAL; /* - * We raced with another vCPU. + * We either raced with another vCPU or the guest PTE + * has been poisoned by an erroneous host access. */ - if (mapping) - return -EAGAIN; + if (mapping) { + ret = kvm_call_hyp_nvhe(__pkvm_vcpu_in_poison_fault); + return ret ? -EFAULT : -EAGAIN; + } ret = kvm_call_hyp_nvhe(__pkvm_host_donate_guest, pfn, gfn); } else { -- 2.53.0.473.g4a7958ca14-goog