From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AB78135EDA5 for ; Mon, 19 Jan 2026 12:48:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768826893; cv=none; b=B46GboTVRXKYl6WbuOqYkea4mSRMKNkv7g8GWyllNx/6sYsZcnjJGO2Cot6u4HAtSe7PVts9STF4/0zDIjihehA4xNfxG2mjnH4w5zYLmutf1zpgwDJDBnjE4QFtAAZvgsaqFAC6R3trMAZgesFUU5EUHPodUB1yIzIG1xZX48c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768826893; c=relaxed/simple; bh=UQUllBTQ8Fml1Y40H7PVGQk/wyiPPN6essaiC/9DWTI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cZ8/ZdmES7aqNnbPMxzuPQmZ9LgFineuO0PGK6GfxyB9257CbYr2Z6ViVRE+Db+fMU6mw+bbnaMLhZmrESQ1ijiuPR+F/45K9mOj5GDdUwr5Uc5oBq09Fsv6XVEFuGNlNAM2vUqjpc7ZcRlhUZgD5Bx/t5Kr4Dq08aonmiA4HH0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cQJdEh4n; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cQJdEh4n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C02B2C19424; Mon, 19 Jan 2026 12:48:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768826893; bh=UQUllBTQ8Fml1Y40H7PVGQk/wyiPPN6essaiC/9DWTI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cQJdEh4nn/ZruAH1oCJz0XkK8kgIyXlTicM3yeWMgaLQHpb/DI7STK/RtvBfUurpf EJnNnpAyTwKhLC7PhRTMqch2I90CvHGD9KDzxEkhvXzBIr1t+9tSfkaRFV9cgOwqum VXvUrxHd/P5XYZu91cX/OsM/x5CIqnDf109w1+7t1BMUAGRQM7/Iqp5c4zzPlNx0g7 rELe5cxInmiw1O957AuCu3KbTATEvpP2VARVuvXVJ17koOpeB58WKwOYgseyJa7wPD 5Hm5bvAt4FWrLfKC7TmMzkcoT1O/UFGgIeUaV+SnJuc+M7lTzs+Uhyhu43b9zyUQfh fAJAdU6StB25g== 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 Subject: [PATCH v2 26/35] KVM: arm64: Return -EFAULT from VCPU_RUN on access to a poisoned pte Date: Mon, 19 Jan 2026 12:46:19 +0000 Message-ID: <20260119124629.2563-27-will@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260119124629.2563-1-will@kernel.org> References: <20260119124629.2563-1-will@kernel.org> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 39e4e588ca4f..c4246c34509a 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 e68b5d24bdad..4ecde9662111 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -570,6 +570,15 @@ 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); @@ -638,6 +647,7 @@ 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 49b309b8d7d2..914b373cfb56 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -898,6 +898,49 @@ 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 d1926cb08c76..14865907610c 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 { -- 2.52.0.457.g6b5491de43-goog