Re: [PATCH 2/9] KVM: arm64: Add a range to __pkvm_host_share_guest()
From: Quentin Perret <hidden>
Date: 2025-02-28 19:06:52
Also in:
kvmarm, lkml
On Friday 28 Feb 2025 at 10:25:18 (+0000), Vincent Donnefort wrote:
+int __pkvm_host_share_guest(u64 pfn, u64 gfn, u64 nr_pages, struct pkvm_hyp_vcpu *vcpu,
enum kvm_pgtable_prot prot)
{
struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
u64 phys = hyp_pfn_to_phys(pfn);
u64 ipa = hyp_pfn_to_phys(gfn);
struct hyp_page *page;
+ u64 size;
int ret;
if (prot & ~KVM_PGTABLE_PROT_RWX)
return -EINVAL;
- ret = check_range_allowed_memory(phys, phys + PAGE_SIZE);I'm not sure it is safe to drop this check here, see below.
+ ret = __guest_check_transition_size(phys, ipa, nr_pages, &size); if (ret) return ret; host_lock_component(); guest_lock_component(vm); - ret = __guest_check_page_state_range(vcpu, ipa, PAGE_SIZE, PKVM_NOPAGE); + ret = __guest_check_page_state_range(vm, ipa, size, PKVM_NOPAGE); if (ret) goto unlock; page = hyp_phys_to_page(phys);
Phys really needs to be a valid memory address here for 'page' to be present in the vmemma -- dereference right below. So we can't rely on the check in __host_check_page_state_range() sadly ...
quoted hunk ↗ jump to hunk
+ ret = __host_check_page_state_range(phys, size, page->host_state); + if (ret) + goto unlock; + switch (page->host_state) { case PKVM_PAGE_OWNED: - WARN_ON(__host_set_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_SHARED_OWNED)); + WARN_ON(__host_set_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED)); break; case PKVM_PAGE_SHARED_OWNED: - if (page->host_share_guest_count) - break; - /* Only host to np-guest multi-sharing is tolerated */ - WARN_ON(1); - fallthrough; + for_each_hyp_page(phys, size, page) { + /* Only host to np-guest multi-sharing is tolerated */ + if (WARN_ON(!page->host_share_guest_count)) { + ret = -EPERM; + goto unlock; + } + } + break; default: ret = -EPERM; goto unlock; } - WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, PAGE_SIZE, phys, + WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, size, phys, pkvm_mkstate(prot, PKVM_PAGE_SHARED_BORROWED), &vcpu->vcpu.arch.pkvm_memcache, 0)); - page->host_share_guest_count++; + __host_update_share_guest_count(phys, size, true); unlock: guest_unlock_component(vm);diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c index 930b677eb9b0..00fd9a524bf7 100644 --- a/arch/arm64/kvm/pkvm.c +++ b/arch/arm64/kvm/pkvm.c@@ -361,7 +361,7 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size, return -EINVAL; lockdep_assert_held_write(&kvm->mmu_lock); - ret = kvm_call_hyp_nvhe(__pkvm_host_share_guest, pfn, gfn, prot); + ret = kvm_call_hyp_nvhe(__pkvm_host_share_guest, pfn, gfn, 1, prot); if (ret) { /* Is the gfn already mapped due to a racing vCPU? */ if (ret == -EPERM)-- 2.48.1.711.g2feabab25a-goog