From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-204.mta0.migadu.com [91.218.175.204]) (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 479AA33A6E9 for ; Fri, 14 Aug 2026 11:45:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.204 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786707956; cv=none; b=bP91mw2pMHX05MACufwhloraruy7CVDOQV2Yl2Cace0Qo2B8oXojfGPb7+1mhe0cNTveP/cpfV0gEDN/5S67mdybyz+y2/l6R7ye78Vxvr58NVJcokKXFQLUrZzkLmi1R5pWQfAzL8BH30oXcWoiLz7V2elqikaUZNtI73Bi6jM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786707956; c=relaxed/simple; bh=NElRwhKXJKskKs7L0lwTCSgGuGKP1HD6hmKGJ40v/N0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZItkMoE4Ru+iVo6US9Fay9ez5DIRrbyrPWHIP5GoK0fjS7B1mApA6++APuwcqEzgWNEREy9V3ML8ziXEoBiHuO/4MyUv5nF9PW5iLC9ElmIhHwlpdybvbOI4QsbBLKesdGM7ImU51miM+KAxTEc3yY61iZbVJi9aldpQsfyNeRM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=q+o6IG4A; arc=none smtp.client-ip=91.218.175.204 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="q+o6IG4A" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=NElRwhKXJKskKs7L0lwTCSgGuGKP1HD6hmKGJ40v/N0=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1786707953; v=1; x=1787312753; b=q+o6IG4AvlFRhAXBwBrDK0GUiZbfDHME/P9E/gOjY++OULnL/qxlQbtzV5j2ep91+Sc3qHap X8nreY0E6I5pPDWCUYSV2MidnZaWyF3d4GgSbY0SOIZcWRmHJuSmELsjUnOQjPS91TJVkSq4fpC d5xzmORm7IMjLgGJF2p9T46U= X-Envelope-To: linux-kernel@vger.kernel.org Received: from localhost.localdomain (2408:823d:2011:2c0:e810:54f9:f0a3:99d) by smtp.migadu.com with ESMTPS id 7749c2dafb5b1cfd; Fri, 14 Aug 2026 11:45:43 +0000 X-Migadu-Flow: FLOW_OUT From: Jinyu Tang To: Anup Patel , Anup Patel , Sean Christopherson Cc: Paolo Bonzini , kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Atish Patra , Paul Walmsley , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Andrew Jones , Conor Dooley , Yong-Xuan Wang , Nutty Liu , Jinyu Tang , Jinyu Tang Subject: [PATCH v3 1/3] KVM: riscv: Implement KVM_PRE_FAULT_MEMORY Date: Fri, 14 Aug 2026 07:45:05 -0400 Message-ID: <20260814114507.583424-2-jinyu.tang@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260814114507.583424-1-jinyu.tang@linux.dev> References: <20260814114507.583424-1-jinyu.tang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The generic KVM_PRE_FAULT_MEMORY ioctl lets userspace populate KVM page tables before running a vCPU over a GPA range. x86 already supports the ioctl, but RISC-V does not expose the capability and has no arch hook. Add the RISC-V arch hook and reuse the existing G-stage fault mapping path with a read access. Report progress using the G-stage mapping returned by the map path, so the ioctl can advance by the actual leaf size that covers the requested GPA. Retry until a mapping is installed or a signal, VM-dead request, or real error is observed. Signed-off-by: Jinyu Tang --- v2 -> v3: - Retry internally when the map path returns success without a visible G-stage mapping, instead of exposing -EAGAIN. (Sashiko) arch/riscv/kvm/Kconfig | 1 + arch/riscv/kvm/gstage.c | 3 +++ arch/riscv/kvm/mmu.c | 42 +++++++++++++++++++++++++++++++++++++++++ arch/riscv/kvm/vm.c | 1 + 4 files changed, 47 insertions(+) diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig index ec2cee0a39e0..8ac209e8ac87 100644 --- a/arch/riscv/kvm/Kconfig +++ b/arch/riscv/kvm/Kconfig @@ -28,6 +28,7 @@ config KVM select KVM_COMMON select KVM_GENERIC_DIRTYLOG_READ_PROTECT select KVM_GENERIC_HARDWARE_ENABLING + select KVM_GENERIC_PRE_FAULT_MEMORY select KVM_MMIO select VIRT_XFER_TO_GUEST_WORK select SCHED_INFO diff --git a/arch/riscv/kvm/gstage.c b/arch/riscv/kvm/gstage.c index e5002cb9cbef..6bd8b8fd6ceb 100644 --- a/arch/riscv/kvm/gstage.c +++ b/arch/riscv/kvm/gstage.c @@ -280,6 +280,9 @@ int kvm_riscv_gstage_map_page(struct kvm_gstage *gstage, out_map->level, true); } else if (ALIGN_DOWN(PFN_PHYS(pte_pfn(ptep_get(ptep))), page_size) == hpa) { kvm_riscv_gstage_update_pte_prot(gstage, ptep_level, gpa, ptep, prot); + out_map->addr = ALIGN_DOWN(gpa, page_size); + out_map->level = ptep_level; + out_map->pte = ptep_get(ptep); return 0; } } diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c index 6035b5ec9503..33d4ba406b0d 100644 --- a/arch/riscv/kvm/mmu.c +++ b/arch/riscv/kvm/mmu.c @@ -748,6 +748,48 @@ int kvm_riscv_mmu_map(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot, return ret; } +long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu, + struct kvm_pre_fault_memory *range) +{ + struct kvm_gstage_mapping out_map = { 0 }; + struct kvm_memory_slot *memslot; + unsigned long map_size; + unsigned long hva; + gpa_t end; + gfn_t gfn; + int ret; + + gfn = gpa_to_gfn(range->gpa); + memslot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); + if (!memslot) + return -ENOENT; + + hva = gfn_to_hva_memslot_prot(memslot, gfn, NULL); + if (kvm_is_error_hva(hva)) + return -ENOENT; + + for (;;) { + if (signal_pending(current)) + return -EINTR; + + if (kvm_check_request(KVM_REQ_VM_DEAD, vcpu)) + return -EIO; + + cond_resched(); + ret = kvm_riscv_mmu_map(vcpu, memslot, range->gpa, hva, false, &out_map); + if (ret) + return ret; + + if (pte_val(out_map.pte)) + break; + } + + map_size = PAGE_SIZE << (out_map.level * kvm_riscv_gstage_index_bits); + end = ALIGN_DOWN(range->gpa, map_size) + map_size; + + return min_t(u64, range->size, end - range->gpa); +} + int kvm_riscv_mmu_alloc_pgd(struct kvm *kvm) { struct page *pgd_page; diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c index a9f083feeb76..58500a19b33b 100644 --- a/arch/riscv/kvm/vm.c +++ b/arch/riscv/kvm/vm.c @@ -187,6 +187,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_MP_STATE: case KVM_CAP_IMMEDIATE_EXIT: case KVM_CAP_SET_GUEST_DEBUG: + case KVM_CAP_PRE_FAULT_MEMORY: r = 1; break; case KVM_CAP_NR_VCPUS: -- 2.43.0