From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ED93A4749E2 for ; Thu, 15 Oct 2026 20:09:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792094955; cv=none; b=WbkPcPuBALShK7iIrhnFgjRuVClDAT7IVlIINGw9DR5Qu2AuzVJUcWpjosEzyTJdZExG7UCFPc4EwxaRc+6AkCnwO5eZdK5qpQrqqY+NcLzuejO3Gv+N7GoJgLdGQP7XnhqGfLQ+wxoOTdEVJbQjYI+/icP8aqWiAilJMWPEMys= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792094955; c=relaxed/simple; bh=YxLFkA27bOezQ/xTbhKCXlt4eRe3P5CCTBEyjjxxyRk=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=bgYN5Ocz/xKuY1dhlQAkFTHCaI6UAdiVVnrhk40Ht1j3Lb08USx4dOewJp/V9VtdRD7JwY0QcrxJXEIUMOMIC9yebpbZcGB/vshH/qkVeSKFzeXtOh1z5/W8+st3s4FtOHlq1apovMtgpm5EVWcNQn4KL7iJOof1f74uhWT3opc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--smostafa.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=IgwDUbD5; arc=none smtp.client-ip=209.85.128.69 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--smostafa.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="IgwDUbD5" Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-4a17574b5easo17700325e9.2 for ; Thu, 15 Oct 2026 13:09:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1792094952; x=1792699752; darn=lists.linux.dev; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=IMjLsiB8JUe1zn3H8B72Qby1JQXygMn6MqjBzblWNdg=; b=IgwDUbD5uC3hEQ/ILKQ1qVa6pVfYXvD/3IVxeJYbH5M+LL5aP/f5wwd5wl3ITfViX9 HF7dvo2QRaEF/MsNuRLLUxZjqyGo0r0zHJUHOO1PNQullZpJXcG3RZ5DqLR2VVu1e3h0 6S5uVaXfiiGMnbBzizt5sYgFw7xCotEFP2CTq2zNvK2T+WNSQciYg1eKO7rkbDOYVG1L 2X30yYZ1QejjdlN3UrGk7QkaBlIfTsofd4HIM7rwriNikHOGxV6utEJ1I3LtaatuzeGT RUGI0xLSEsJrzjo0A36P9VTzT6yzIs/8ABs72Cp3wX4HAGAlgMHYKCx9DFF/Vo92RzP0 Ey2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1792094952; x=1792699752; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=IMjLsiB8JUe1zn3H8B72Qby1JQXygMn6MqjBzblWNdg=; b=Y4uZLB80VzFLjSkVA099UrlDpT54/mYfolRR9Hlrjo2F318I8RYDQPd1HeDRPm76iN O4oBzcGaVsveMay7UqRkY8PIv8VtIuaxnNZ3M11HW+kgweNDDo7eVYNgwpWc3GvcKaSW 7hZaBhglvrZbxKvYZC6Tt7ijNmp75cwy+KWmdGLp1lK+yisxUPlBGAQ+7U75VPXsDLmJ zEadPEyHNafFXGeW2xmWmQx21gk8lCq/gZHUSvM7v2ggpQ3l4ceW4RQAkBNg3xl1m9aW BLavRE0WAGGc+3Hogo+4NGTvag1LlKF6BCY4Lcnx3joma/szlO85a3DLA+x3zbbb878A XbtQ== X-Forwarded-Encrypted: i=1; AKwUvBwWr7ijZ7EeChy84lJ+b7CyEQg02McLuGis6kqGXMXDfrKwsCc29JIeLHCylvK1AuA7lGVA/fY=@lists.linux.dev X-Gm-Message-State: AFq9FYKchbMHZAfAs/Xi/lp1sOiY7oaIPfFcfNd4YaSjqzQXsJZj5pKj iELwbq/HEYmdvGP1//ezUVUn5A1TuZCRHF0cLDtvpogJ9p0tfHezliFfuCtwKGzazOxMmVj/vGk MicW+lGwpRhdzUg== X-Received: from wmbd18.prod.google.com ([2002:a05:600c:58d2:b0:4a1:7ec4:6621]) (user=smostafa job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600d:17:b0:4a1:9663:7639 with SMTP id 5b1f17b1804b1-4a196637a39mr305024695e9.34.1792094952096; Thu, 15 Oct 2026 13:09:12 -0700 (PDT) Date: Thu, 15 Oct 2026 20:08:32 +0000 In-Reply-To: <20261015200903.2735565-1-smostafa@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20261015200903.2735565-1-smostafa@google.com> X-Mailer: git-send-email 2.56.0.176.g3575e65682-goog Message-ID: <20261015200903.2735565-2-smostafa@google.com> Subject: [PATCH v9 01/25] KVM: arm64: Donate MMIO to the hypervisor From: Mostafa Saleh To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, iommu@lists.linux.dev Cc: catalin.marinas@arm.com, will@kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, joro@8bytes.org, jgg@ziepe.ca, mark.rutland@arm.com, qperret@google.com, tabba@google.com, vdonnefort@google.com, nicolinc@nvidia.com, Mostafa Saleh Content-Type: text/plain; charset="UTF-8" Add __pkvm_host_donate_hyp_mmio() so IOMMU drivers in the hypervisor can take ownership of the IOMMU MMIO. The range is mapped in the hypervisor private range and annotated as owned by the hypervisor in the host stage-2, so host accesses fault and further donations of the same range are refused. MMIO has no struct hyp_page, so the annotation is the only state, and a dedicated function is simpler than teaching the memory donation path about MMIO. Donation is only allowed before the host is de-privileged, which is when the hypervisor IOMMU drivers initialise. Make kvm_pgtable_stage2_unmap() leave invalid counted PTEs (annotations) in place. host_stage2_unmap_dev_all() unmaps all non-memory ranges to recycle page-table pages under memory pressure, and would otherwise drop the annotation and let the host fault the MMIO back in. No caller depends on the old behaviour: host_stage2_unmap_dev_all() only covers non-memory ranges, where no annotation existed until now, and the guest unmap paths check that the PTE is valid first. Returning an error for counted PTEs instead is not an option, as a non-zero visitor return stops the walk, which would abort recycling at the first hypervisor-owned MMIO page and inject an abort into the host for an unrelated address. Add __pkvm_hyp_donate_host_mmio() for the IOMMU driver error path. It unmaps the range from the hypervisor and maps it back in the host stage-2. The private VA range cannot be reclaimed and is leaked, as with every other failed private mapping. Signed-off-by: Mostafa Saleh --- arch/arm64/include/asm/kvm_pgtable.h | 2 + arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 10 ++ arch/arm64/kvm/hyp/nvhe/mem_protect.c | 99 ++++++++++++++++++- arch/arm64/kvm/hyp/pgtable.c | 8 +- 4 files changed, 112 insertions(+), 7 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index 41a8687938eb..20b1adb8a058 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -713,6 +713,8 @@ int kvm_pgtable_stage2_annotate(struct kvm_pgtable *pgt, u64 addr, u64 size, * freed. Unmapping a cacheable page will ensure that it is clean to the PoC if * FWB is not supported by the CPU. * + * Invalid counted PTEs (annotations) are left in place. + * * Return: 0 on success, negative error code on failure. */ int kvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size); diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h index ec85a9547120..c9c3e2dbbe58 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h @@ -36,6 +36,16 @@ 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); +/* + * Donate MMIO range to the hypervisor, it will be mapped in the hypervisor's + * private range and unmapped from the host stage-2. + */ +int __pkvm_host_donate_hyp_mmio(u64 pfn, u64 nr_pages, unsigned long *haddr); +/* + * Undo __pkvm_host_donate_hyp_mmio(), typically on an error path. @haddr is + * the address returned by the donation. + */ +int __pkvm_hyp_donate_host_mmio(u64 pfn, u64 nr_pages, unsigned long haddr); 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); diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index a6a47c1e058b..75d250ca809c 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -385,7 +385,11 @@ static int host_stage2_unmap_dev_all(void) u64 addr = 0; int i, ret; - /* Unmap all non-memory regions to recycle the pages */ + /* + * Unmap all non-memory regions to recycle the pages. + * That relies on kvm_pgtable_stage2_unmap() not clearing + * counted PTEs which include hypervisor MMIO. + */ for (i = 0; i < hyp_memblock_nr; i++, addr = reg->base + reg->size) { reg = &hyp_memory[i]; ret = kvm_pgtable_stage2_unmap(pgt, addr, reg->base - addr); @@ -1146,6 +1150,99 @@ int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages) return ret; } +int __pkvm_host_donate_hyp_mmio(u64 pfn, u64 nr_pages, unsigned long *haddr) +{ + u64 phys = hyp_pfn_to_phys(pfn); + u64 size = PAGE_SIZE * nr_pages; + unsigned long addr; + kvm_pte_t pte; + u64 offset; + int ret; + + /* Only before de-privilege. */ + if (static_branch_unlikely(&kvm_protected_mode_initialized)) + return -EPERM; + + if (!pfn_range_is_valid(pfn, nr_pages)) + return -EINVAL; + + host_lock_component(); + for (offset = 0; offset < size; offset += PAGE_SIZE) { + if (addr_is_memory(phys + offset)) { + ret = -EINVAL; + goto unlock; + } + ret = kvm_pgtable_get_leaf(&host_mmu.pgt, phys + offset, &pte, NULL); + if (ret) + goto unlock; + if (pte && !kvm_pte_valid(pte)) { + ret = -EPERM; + goto unlock; + } + } + + ret = __pkvm_create_private_mapping(phys, size, PAGE_HYP_DEVICE, &addr); + if (ret) + goto unlock; + + /* + * Mark the range as owned by the hypervisor in the host stage-2. + * The annotation makes host accesses fault, and is retained by + * host_stage2_unmap_dev_all() + */ + ret = host_stage2_try(kvm_pgtable_stage2_annotate, &host_mmu.pgt, + phys, size, &host_s2_pool, + KVM_HOST_INVALID_PTE_TYPE_DONATION, + FIELD_PREP(KVM_HOST_DONATION_PTE_OWNER_MASK, PKVM_ID_HYP)); + if (ret) { + hyp_lock_component(); + WARN_ON(kvm_pgtable_hyp_unmap(&pkvm_pgtable, addr, size) != size); + hyp_unlock_component(); + } else { + *haddr = addr; + } +unlock: + host_unlock_component(); + return ret; +} + +int __pkvm_hyp_donate_host_mmio(u64 pfn, u64 nr_pages, unsigned long haddr) +{ + u64 phys = hyp_pfn_to_phys(pfn); + u64 size = PAGE_SIZE * nr_pages; + kvm_pte_t pte; + u64 offset; + int ret = 0; + + if (static_branch_unlikely(&kvm_protected_mode_initialized)) + return -EPERM; + + if (!pfn_range_is_valid(pfn, nr_pages)) + return -EINVAL; + + host_lock_component(); + hyp_lock_component(); + for (offset = 0; offset < size; offset += PAGE_SIZE) { + if (addr_is_memory(phys + offset)) { + ret = -EINVAL; + goto unlock; + } + ret = kvm_pgtable_get_leaf(&host_mmu.pgt, phys + offset, &pte, NULL); + if (ret) + goto unlock; + if (!host_stage2_pte_is_hyp_owned(pte)) { + ret = -EPERM; + goto unlock; + } + } + WARN_ON(kvm_pgtable_hyp_unmap(&pkvm_pgtable, haddr, size) != size); + WARN_ON(host_stage2_idmap_locked(phys, size, PKVM_HOST_MMIO_PROT)); +unlock: + hyp_unlock_component(); + host_unlock_component(); + return ret; +} + int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages) { u64 phys = hyp_pfn_to_phys(pfn); diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index b74dd5ce1efd..58b74450c824 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -1161,13 +1161,9 @@ static int stage2_unmap_walker(const struct kvm_pgtable_visit_ctx *ctx, kvm_pte_t *childp = NULL; bool need_flush = false; - if (!kvm_pte_valid(ctx->old)) { - if (stage2_pte_is_counted(ctx->old)) { - kvm_clear_pte(ctx->ptep); - mm_ops->put_page(ctx->ptep); - } + /* Invalid PTEs are left in place, including annotations. */ + if (!kvm_pte_valid(ctx->old)) return 0; - } if (kvm_pte_table(ctx->old, ctx->level)) { childp = kvm_pte_follow(ctx->old, mm_ops); -- 2.56.0.176.g3575e65682-goog