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 9EB42CCF2F6 for ; Mon, 19 Jan 2026 12:48:04 +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=cwjjBihMMBDYUKGZisAOJ6EHFb4CuClur1VhwvcLDqQ=; b=J0gT/IX3IMKdMVMC0qltlj8PQm IAhfo5HJUjiZ/mJy+rc0iZasBugbzNVfHiMMwoMOD4AK8tBlNDfYT2AybZmiuKM8wQNnaLxBmTEXV LIVY303XEUkofndE5HvyZs0fObolr6+dxECCCwrV8Q3L9D9FRaHazkwOQLddnVB2ZoFgdlw/UTv1z MDACZFl6dZe3+46IpmFyVL5wA0dKwymIUA9X0cOXKW9xTrl2aW04KraVt8kqxwx5lN/Z2wYClK+9n mlXUlug6Yr95bxn69jtx3f8HK7qObiE9s8ln0QwPxpUf5bT6JZjGkU1xbuh7qY7nr9aPjPi+QmrIb U7M0qA5g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vhoff-000000023cG-3uAF; Mon, 19 Jan 2026 12:47:51 +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 1vhofU-000000023SG-1Ebh for linux-arm-kernel@lists.infradead.org; Mon, 19 Jan 2026 12:47:42 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id ADCB860167; Mon, 19 Jan 2026 12:47:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5F53C116C6; Mon, 19 Jan 2026 12:47:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768826859; bh=4ru9p1aqsvFT0+hCr8OEqQDw4WyTq5L2XKtlgIREc/8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YFava6a7NXPNSYP24J7tfRxplcfTDONxUwEATBCAE9ons+YTEzWLaPnGEAPqvhJlC mtEzy8elM/bteTLRbc/uR+fjiHMX+aZZnAjDOVy/yfzH7JyBObtVoW41wvbwu8zAGr edZk+fCMJx8k+yL3WeWO+891lwHNx9kq5KGu6MJ9K91Wxaxj4Sb+neACc6Uq5tH9UA r+AXSyRjMmHx9bVNmC/KgN6gv14a7KP7bm7qAbUBgnxB3aszycchkS6vXguWor+VLw sXTPBmDDwa0vkk693ou4voLQLazlSrLI79mUyTIb3dV+DXbciIkR1FxPGWwU441bkV 7VOb+M+hc8wNA== 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 15/35] KVM: arm64: Introduce __pkvm_reclaim_dying_guest_page() Date: Mon, 19 Jan 2026 12:46:08 +0000 Message-ID: <20260119124629.2563-16-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> 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 To enable reclaim of pages from a protected VM during teardown, introduce a new hypercall to reclaim a single page from a protected guest that is in the dying state. Since the EL2 code is non-preemptible, the new hypercall deliberately acts on a single page at a time so as to allow EL1 to reschedule frequently during the teardown operation. Reviewed-by: Vincent Donnefort Co-developed-by: Quentin Perret Signed-off-by: Quentin Perret 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/include/nvhe/pkvm.h | 1 + arch/arm64/kvm/hyp/nvhe/hyp-main.c | 9 +++ arch/arm64/kvm/hyp/nvhe/mem_protect.c | 79 +++++++++++++++++++ arch/arm64/kvm/hyp/nvhe/pkvm.c | 14 ++++ 6 files changed, 105 insertions(+) diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index 2750b75b5b8f..2e7e8e7771f6 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_reclaim_dying_guest_page, __KVM_HOST_SMCCC_FUNC___pkvm_start_teardown_vm, __KVM_HOST_SMCCC_FUNC___pkvm_finalize_teardown_vm, __KVM_HOST_SMCCC_FUNC___pkvm_vcpu_load, diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h index 9c0cc53d1dc9..cde38a556049 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_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, enum kvm_pgtable_prot prot); int __pkvm_host_unshare_guest(u64 gfn, u64 nr_pages, struct pkvm_hyp_vm *hyp_vm); diff --git a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h index 04c7ca703014..506831804f64 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h +++ b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h @@ -74,6 +74,7 @@ int __pkvm_init_vm(struct kvm *host_kvm, unsigned long vm_hva, int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu, unsigned long vcpu_hva); +int __pkvm_reclaim_dying_guest_page(pkvm_handle_t handle, u64 gfn); int __pkvm_start_teardown_vm(pkvm_handle_t handle); int __pkvm_finalize_teardown_vm(pkvm_handle_t handle); diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index c04300b51c9a..f43c50ae2d81 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -570,6 +570,14 @@ 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_reclaim_dying_guest_page(struct kvm_cpu_context *host_ctxt) +{ + DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1); + DECLARE_REG(u64, gfn, host_ctxt, 2); + + cpu_reg(host_ctxt, 1) = __pkvm_reclaim_dying_guest_page(handle, gfn); +} + static void handle___pkvm_start_teardown_vm(struct kvm_cpu_context *host_ctxt) { DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1); @@ -623,6 +631,7 @@ static const hcall_t host_hcall[] = { HANDLE_FUNC(__pkvm_unreserve_vm), HANDLE_FUNC(__pkvm_init_vm), HANDLE_FUNC(__pkvm_init_vcpu), + HANDLE_FUNC(__pkvm_reclaim_dying_guest_page), HANDLE_FUNC(__pkvm_start_teardown_vm), HANDLE_FUNC(__pkvm_finalize_teardown_vm), HANDLE_FUNC(__pkvm_vcpu_load), diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index f24e8ce2c40c..ef21e8e7a734 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -736,6 +736,32 @@ static int __guest_check_page_state_range(struct pkvm_hyp_vm *vm, u64 addr, return check_page_state_range(&vm->pgt, addr, size, &d); } +static int get_valid_guest_pte(struct pkvm_hyp_vm *vm, u64 ipa, kvm_pte_t *ptep, u64 *physp) +{ + kvm_pte_t pte; + u64 phys; + s8 level; + int ret; + + ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level); + if (ret) + return ret; + if (!kvm_pte_valid(pte)) + return -ENOENT; + if (level != KVM_PGTABLE_LAST_LEVEL) + return -E2BIG; + + phys = kvm_pte_to_phys(pte); + ret = check_range_allowed_memory(phys, phys + PAGE_SIZE); + if (WARN_ON(ret)) + return ret; + + *ptep = pte; + *physp = phys; + + return 0; +} + int __pkvm_host_share_hyp(u64 pfn) { u64 phys = hyp_pfn_to_phys(pfn); @@ -969,6 +995,59 @@ static int __guest_check_transition_size(u64 phys, u64 ipa, u64 nr_pages, u64 *s return 0; } +static void hyp_poison_page(phys_addr_t phys) +{ + void *addr = hyp_fixmap_map(phys); + + memset(addr, 0, PAGE_SIZE); + /* + * Prefer kvm_flush_dcache_to_poc() over __clean_dcache_guest_page() + * here as the latter may elide the CMO under the assumption that FWB + * will be enabled on CPUs that support it. This is incorrect for the + * host stage-2 and would otherwise lead to a malicious host potentially + * being able to read the contents of newly reclaimed guest pages. + */ + kvm_flush_dcache_to_poc(addr, PAGE_SIZE); + hyp_fixmap_unmap(); +} + +int __pkvm_host_reclaim_page_guest(u64 gfn, struct pkvm_hyp_vm *vm) +{ + u64 ipa = hyp_pfn_to_phys(gfn); + kvm_pte_t pte; + u64 phys; + int ret; + + host_lock_component(); + guest_lock_component(vm); + + ret = get_valid_guest_pte(vm, ipa, &pte, &phys); + if (ret) + goto unlock; + + switch (guest_get_page_state(pte, ipa)) { + case PKVM_PAGE_OWNED: + WARN_ON(__host_check_page_state_range(phys, PAGE_SIZE, PKVM_NOPAGE)); + hyp_poison_page(phys); + break; + case PKVM_PAGE_SHARED_OWNED: + WARN_ON(__host_check_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_SHARED_BORROWED)); + break; + default: + ret = -EPERM; + goto unlock; + } + + WARN_ON(kvm_pgtable_stage2_unmap(&vm->pgt, ipa, PAGE_SIZE)); + WARN_ON(host_stage2_set_owner_locked(phys, PAGE_SIZE, PKVM_ID_HOST)); + +unlock: + guest_unlock_component(vm); + host_unlock_component(); + + return ret; +} + int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu) { struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu); diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c index 7f8191f96fc3..9f0997150cf5 100644 --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c @@ -832,6 +832,20 @@ teardown_donated_memory(struct kvm_hyp_memcache *mc, void *addr, size_t size) unmap_donated_memory_noclear(addr, size); } +int __pkvm_reclaim_dying_guest_page(pkvm_handle_t handle, u64 gfn) +{ + struct pkvm_hyp_vm *hyp_vm; + int ret = -EINVAL; + + hyp_spin_lock(&vm_table_lock); + hyp_vm = get_vm_by_handle(handle); + if (hyp_vm && hyp_vm->kvm.arch.pkvm.is_dying) + ret = __pkvm_host_reclaim_page_guest(gfn, hyp_vm); + hyp_spin_unlock(&vm_table_lock); + + return ret; +} + int __pkvm_start_teardown_vm(pkvm_handle_t handle) { struct pkvm_hyp_vm *hyp_vm; -- 2.52.0.457.g6b5491de43-goog