Commit 8c5fa376 authored by Fangyu Yu's avatar Fangyu Yu Committed by Anup Patel
Browse files

RISC-V: KVM: Remove automatic I/O mapping for VM_PFNMAP 



As of commit aac6db75 ("vfio/pci: Use unmap_mapping_range()"),
vm_pgoff may no longer guaranteed to hold the PFN for VM_PFNMAP
regions. Using vma->vm_pgoff to derive the HPA here may therefore
produce incorrect mappings.

Instead, I/O mappings for such regions can be established on-demand
during g-stage page faults, making the upfront ioremap in this path
is unnecessary.

Fixes: aac6db75 ("vfio/pci: Use unmap_mapping_range()")
Signed-off-by: default avatarFangyu Yu <fangyu.yu@linux.alibaba.com>
Tested-by: default avatarDaniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: default avatarGuo Ren <guoren@kernel.org>
Reviewed-by: default avatarAnup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251021142131.78796-1-fangyu.yu@linux.alibaba.com


Signed-off-by: default avatarAnup Patel <anup@brainfault.org>
parent 873f10cf

arch/riscv/kvm/mmu.c

+2 −23
Original line number Diff line number Diff line
@@ -171,7 +171,6 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, 
				enum kvm_mr_change change)

{

	hva_t hva, reg_end, size;

	gpa_t base_gpa;

	bool writable;

	int ret = 0;
@@ -190,15 +189,13 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, 
	hva = new->userspace_addr;

	size = new->npages << PAGE_SHIFT;

	reg_end = hva + size;

	base_gpa = new->base_gfn << PAGE_SHIFT;

	writable = !(new->flags & KVM_MEM_READONLY);



	mmap_read_lock(current->mm);



	/*

	 * A memory region could potentially cover multiple VMAs, and

	 * any holes between them, so iterate over all of them to find

	 * out if we can map any of them right now.

	 * any holes between them, so iterate over all of them.

	 *

	 *     +--------------------------------------------+

	 * +---------------+----------------+   +----------------+
@@ -209,7 +206,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, 
	 */

	do {

		struct vm_area_struct *vma;

		hva_t vm_start, vm_end;

		hva_t vm_end;



		vma = find_vma_intersection(current->mm, hva, reg_end);

		if (!vma)
@@ -225,36 +222,18 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, 
		}



		/* Take the intersection of this VMA with the memory region */

		vm_start = max(hva, vma->vm_start);

		vm_end = min(reg_end, vma->vm_end);



		if (vma->vm_flags & VM_PFNMAP) {

			gpa_t gpa = base_gpa + (vm_start - hva);

			phys_addr_t pa;



			pa = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;

			pa += vm_start - vma->vm_start;



			/* IO region dirty page logging not allowed */

			if (new->flags & KVM_MEM_LOG_DIRTY_PAGES) {

				ret = -EINVAL;

				goto out;

			}



			ret = kvm_riscv_mmu_ioremap(kvm, gpa, pa, vm_end - vm_start,

						    writable, false);

			if (ret)

				break;

		}

		hva = vm_end;

	} while (hva < reg_end);



	if (change == KVM_MR_FLAGS_ONLY)

		goto out;



	if (ret)

		kvm_riscv_mmu_iounmap(kvm, base_gpa, size);



out:

	mmap_read_unlock(current->mm);

	return ret;