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 D0AB0F33A79 for ; Thu, 5 Mar 2026 14:46:03 +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=b8MP6Fh1w6R+sKcxRelLUkGcxKqrs99KdxZNDTW8fvQ=; b=Rd1cj6RNnFIwCUiJuAEl94ORkd zpMe3d0hofEoSa/Yda679BbgXmv0cLfTbfwkD8rES+OTGv98pAA4opLsmP2YDLZPBU9fVMB1kOsIH 0nMAqENsVr2JjyJRtuCenIVG0lBeBI9jBC/AN4HLrH9zPJ5VmwEclu5X8412mtVRbfHWFmanZgvsd bX6MUni5/g7eEdKuYNwJNgytAxxBB/JtdKyC9T2Iu+jns6OpAWXNUFYjNnf4d0sooUYmE8KbOas0r 8VOi0DEEPUhll9w+5IM7rURUkOEp2LKmDhP985HPBesuv88fUvJwEvxFP5g2rdEjuAMsW1Nn7ZW8L RugSPw4g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vy9xd-000000022nI-1su4; Thu, 05 Mar 2026 14:45:57 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vy9xc-000000022kJ-0XPF for linux-arm-kernel@bombadil.infradead.org; Thu, 05 Mar 2026 14:45:56 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:MIME-Version :References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=b8MP6Fh1w6R+sKcxRelLUkGcxKqrs99KdxZNDTW8fvQ=; b=eeRgCajCJCiaXyOwBaOZ2GhXhQ 4uV+dke9dFYxdeMX6sHTooTXDfukxo8qSpcvYqq2GY/4lMzM1CYT0fSEVRLpU+3ss9DbJhpv54/2z khrVI2nCXwKCoXJAlJdWMwe88SQmsutl80hLWECEe54HbGn4G8CvqhPu3kAST/uW0PLtw5Hn+SpFt b5KsZ0+TcqMKchkjQIQNbAlKQNiS2P7zMCDcSp2UPMKrvCRCYbmMBxCz0kvFI0GafQEtJiA0wd+W+ UP84iwIHJ9dXKjMqEpvjzedkZAvAUTJ9y8WDzxngab69RJ3HgcPleDnLN1ihe0Oc2iM6e6IVSJSIF Zl+Ymsjg==; Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by desiato.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vy9xY-00000006yZH-38K8 for linux-arm-kernel@lists.infradead.org; Thu, 05 Mar 2026 14:45:54 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 7765C42CBC; Thu, 5 Mar 2026 14:45:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77C73C116C6; Thu, 5 Mar 2026 14:45:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772721951; bh=v3KVb0ei2XKe7JH4mQ0tL3ZhknFGX3kJj3Ixv2atPic=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ELDBMzL+5yewdZ8eTaRHY/0NCdHbmhFT7Xs7YJozcKml/YJ06vvg5QvZmdJXC3yru Mx78ooyba6FkO5U3rymr9mgEEyB89nX8LZYvt5IzUDTCvZdYj4qT3Edbt5dD6GsMdl IWLcmosBlBlarwAG9c1yQ7HQyWbNpvHku+mq8Dn4nmgT+/vlSaPWT8e/HXdEy2CmQK ZsexCB3Qvm1ie2NavWdvrevDQRDQ3MqqYBv5oDM6bsRU/TxCBw4uPHZRj4antrOkYK 8Bgu8f3CvzYZBOOLSt6Mb8A77MTcHDA864vRUfAc07YzGoTaKGxQcZbwYClvU2lBPC 2EWsOOMMsxskQ== 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 29/36] KVM: arm64: Implement the MEM_UNSHARE hypercall for protected VMs Date: Thu, 5 Mar 2026 14:43:42 +0000 Message-ID: <20260305144351.17071-30-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-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260305_144553_247174_06E7E3BA X-CRM114-Status: GOOD ( 13.57 ) 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 Implement the ARM_SMCCC_KVM_FUNC_MEM_UNSHARE hypercall to allow protected VMs to unshare memory that was previously shared with the host using the ARM_SMCCC_KVM_FUNC_MEM_SHARE hypercall. Reviewed-by: Vincent Donnefort Signed-off-by: Will Deacon --- arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 1 + arch/arm64/kvm/hyp/nvhe/mem_protect.c | 34 +++++++++++++++++++ arch/arm64/kvm/hyp/nvhe/pkvm.c | 22 ++++++++++++ 3 files changed, 57 insertions(+) diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h index 42fd60c5cfc9..e41a128b0854 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h @@ -36,6 +36,7 @@ extern unsigned long hyp_nr_cpus; int __pkvm_prot_finalize(void); int __pkvm_host_share_hyp(u64 pfn); int __pkvm_guest_share_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn); +int __pkvm_guest_unshare_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn); int __pkvm_host_unshare_hyp(u64 pfn); int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages); int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages); diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index 22d456ab15a6..4451955ac767 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -991,6 +991,40 @@ int __pkvm_guest_share_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn) return ret; } +int __pkvm_guest_unshare_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn) +{ + struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu); + u64 meta, phys, ipa = hyp_pfn_to_phys(gfn); + kvm_pte_t pte; + int ret; + + host_lock_component(); + guest_lock_component(vm); + + ret = get_valid_guest_pte(vm, ipa, &pte, &phys); + if (ret) + goto unlock; + + ret = -EPERM; + if (pkvm_getstate(kvm_pgtable_stage2_pte_prot(pte)) != PKVM_PAGE_SHARED_OWNED) + goto unlock; + if (__host_check_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_SHARED_BORROWED)) + goto unlock; + + ret = 0; + meta = host_stage2_encode_gfn_meta(vm, gfn); + WARN_ON(host_stage2_set_owner_metadata_locked(phys, PAGE_SIZE, + PKVM_ID_GUEST, meta)); + WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, PAGE_SIZE, phys, + pkvm_mkstate(KVM_PGTABLE_PROT_RWX, PKVM_PAGE_OWNED), + &vcpu->vcpu.arch.pkvm_memcache, 0)); +unlock: + guest_unlock_component(vm); + host_unlock_component(); + + return ret; +} + int __pkvm_host_unshare_hyp(u64 pfn) { u64 phys = hyp_pfn_to_phys(pfn); diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c index 1dc9225073c4..ebfd9904ede6 100644 --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c @@ -1019,6 +1019,19 @@ static bool pkvm_memshare_call(u64 *ret, struct kvm_vcpu *vcpu, u64 *exit_code) return false; } +static void pkvm_memunshare_call(u64 *ret, struct kvm_vcpu *vcpu) +{ + struct pkvm_hyp_vcpu *hyp_vcpu; + u64 ipa = smccc_get_arg1(vcpu); + + if (!PAGE_ALIGNED(ipa)) + return; + + hyp_vcpu = container_of(vcpu, struct pkvm_hyp_vcpu, vcpu); + if (!__pkvm_guest_unshare_host(hyp_vcpu, hyp_phys_to_pfn(ipa))) + ret[0] = SMCCC_RET_SUCCESS; +} + /* * Handler for protected VM HVC calls. * @@ -1036,6 +1049,7 @@ bool kvm_handle_pvm_hvc64(struct kvm_vcpu *vcpu, u64 *exit_code) val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES); val[0] |= BIT(ARM_SMCCC_KVM_FUNC_HYP_MEMINFO); val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MEM_SHARE); + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MEM_UNSHARE); break; case ARM_SMCCC_VENDOR_HYP_KVM_HYP_MEMINFO_FUNC_ID: if (smccc_get_arg1(vcpu) || @@ -1054,6 +1068,14 @@ bool kvm_handle_pvm_hvc64(struct kvm_vcpu *vcpu, u64 *exit_code) handled = pkvm_memshare_call(val, vcpu, exit_code); break; + case ARM_SMCCC_VENDOR_HYP_KVM_MEM_UNSHARE_FUNC_ID: + if (smccc_get_arg2(vcpu) || + smccc_get_arg3(vcpu)) { + break; + } + + pkvm_memunshare_call(val, vcpu); + break; default: /* Punt everything else back to the host, for now. */ handled = false; -- 2.53.0.473.g4a7958ca14-goog