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 201C4CCF2F9 for ; Mon, 19 Jan 2026 12:49:17 +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=ZuiYLXlGkYHPFeaj/0AJYpJIdR9urN8Fau32/NbTpTw=; b=Z37lifQOeO0MpgjXnisrCoWkin XnvnRWtnPQAu/h+7TwyvK7RkqSjkAy7ydNNFbp/eBWXL53BXbJ3+FH8NC3IpU27Cjjd9O/j1CIKi4 fn9CbgmUbLIjYcmR4fFjNdNOMsdOUhjX5g+E6S4h1k/IxwQoedCLm9FzRFF+xrcyKzwPr93BxPHOr +1oTXFLPnK2zIUlT6lUWZId/Q//gs1hCcPfbfxAkYycdLfXp6svgieyISgcp2PVDkCAW6Zu7Asv6A 5lUMpiF3CKYnRo20RcfKNaxdGQqXY8SRM5dXxh8Wkis+Q0QGKBuLv5EjJwOOxsrVzJqhXU79iE5cw I34EC/dA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vhogn-000000024Wq-3UuH; Mon, 19 Jan 2026 12:49:01 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vhogB-000000023zW-1j8h for linux-arm-kernel@lists.infradead.org; Mon, 19 Jan 2026 12:48:24 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id C6AF56016C; Mon, 19 Jan 2026 12:48:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3F4EC116C6; Mon, 19 Jan 2026 12:48:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768826902; bh=dVWfvIfyOr8qBQ0+yJXKHDLffmDd3mqOBXloDEZtcSo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YytEKQKNsYNvUTGtBZpw1eRz9f4ruIfgzsE+2Nh0UV4owUExbIQgKxVAgebuh5shd DehqHJnDTk3JuNYxzuSMDvvZFAE45uoeosKlvp/zAuXXhThlmPBeDCs7aW9U2LqQsz Lc3YpJAG68nv54lVquz91ooXTllfRMy12wkre24rM7z1RwzGxuMybtUP0Ss0FE5Xu/ Rg6cTIDES9jHcXA02erKdr9En24d4zKrfAq/mfVAx+ykjEkuZQPlriBMAHyMG6tv/5 1lx8Z0SfZM8NvaSYJ0oVAqF5+LrPFCxQiwMvnqi5EIHFA6qt7LoAQzSURGw6LRixhh MaamyBuoAD6qQ== 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 29/35] KVM: arm64: Implement the MEM_UNSHARE hypercall for protected VMs Date: Mon, 19 Jan 2026 12:46:22 +0000 Message-ID: <20260119124629.2563-30-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 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 7535a45565f4..3969a92dc3e2 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -999,6 +999,40 @@ 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 4133556560d9..4ddb3d70f9c0 100644 --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c @@ -989,6 +989,19 @@ 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. * @@ -1006,6 +1019,7 @@ 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) || @@ -1024,6 +1038,14 @@ 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; -- 2.52.0.457.g6b5491de43-goog