Commit 3c164eb9 authored by Oliver Upton's avatar Oliver Upton Committed by Marc Zyngier
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KVM: arm64: nv: Do not block when unmapping stage-2 if disallowed 



Right now the nested code allows unmap operations on a shadow stage-2 to
block unconditionally. This is wrong in a couple places, such as a
non-blocking MMU notifier or on the back of a sched_in() notifier as
part of shadow MMU recycling.

Carry through whether or not blocking is allowed to
kvm_pgtable_stage2_unmap(). This 'fixes' an issue where stage-2 MMU
reclaim would precipitate a stack overflow from a pile of kvm_sched_in()
callbacks, all trying to recycle a stage-2 MMU.

Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241007233028.2236133-3-oliver.upton@linux.dev


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 6ded46b5

arch/arm64/include/asm/kvm_mmu.h

+2 −1
Original line number Diff line number Diff line
@@ -166,7 +166,8 @@ int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size, 
int create_hyp_stack(phys_addr_t phys_addr, unsigned long *haddr);

void __init free_hyp_pgds(void);



void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size);

void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start,

			    u64 size, bool may_block);

void kvm_stage2_flush_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end);

void kvm_stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end);

arch/arm64/include/asm/kvm_nested.h

+1 −1
Original line number Diff line number Diff line
@@ -124,7 +124,7 @@ extern int kvm_s2_handle_perm_fault(struct kvm_vcpu *vcpu, 
				    struct kvm_s2_trans *trans);

extern int kvm_inject_s2_fault(struct kvm_vcpu *vcpu, u64 esr_el2);

extern void kvm_nested_s2_wp(struct kvm *kvm);

extern void kvm_nested_s2_unmap(struct kvm *kvm);

extern void kvm_nested_s2_unmap(struct kvm *kvm, bool may_block);

extern void kvm_nested_s2_flush(struct kvm *kvm);



unsigned long compute_tlb_inval_range(struct kvm_s2_mmu *mmu, u64 val);

arch/arm64/kvm/mmu.c

+8 −7
Original line number Diff line number Diff line
@@ -328,9 +328,10 @@ static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 
				   may_block));

}



void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size)

void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start,

			    u64 size, bool may_block)

{

	__unmap_stage2_range(mmu, start, size, true);

	__unmap_stage2_range(mmu, start, size, may_block);

}



void kvm_stage2_flush_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end)
@@ -1015,7 +1016,7 @@ static void stage2_unmap_memslot(struct kvm *kvm, 


		if (!(vma->vm_flags & VM_PFNMAP)) {

			gpa_t gpa = addr + (vm_start - memslot->userspace_addr);

			kvm_stage2_unmap_range(&kvm->arch.mmu, gpa, vm_end - vm_start);

			kvm_stage2_unmap_range(&kvm->arch.mmu, gpa, vm_end - vm_start, true);

		}

		hva = vm_end;

	} while (hva < reg_end);
@@ -1042,7 +1043,7 @@ void stage2_unmap_vm(struct kvm *kvm) 
	kvm_for_each_memslot(memslot, bkt, slots)

		stage2_unmap_memslot(kvm, memslot);



	kvm_nested_s2_unmap(kvm);

	kvm_nested_s2_unmap(kvm, true);



	write_unlock(&kvm->mmu_lock);

	mmap_read_unlock(current->mm);
@@ -1912,7 +1913,7 @@ bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) 
			     (range->end - range->start) << PAGE_SHIFT,

			     range->may_block);



	kvm_nested_s2_unmap(kvm);

	kvm_nested_s2_unmap(kvm, range->may_block);

	return false;

}
@@ -2179,8 +2180,8 @@ void kvm_arch_flush_shadow_memslot(struct kvm *kvm, 
	phys_addr_t size = slot->npages << PAGE_SHIFT;



	write_lock(&kvm->mmu_lock);

	kvm_stage2_unmap_range(&kvm->arch.mmu, gpa, size);

	kvm_nested_s2_unmap(kvm);

	kvm_stage2_unmap_range(&kvm->arch.mmu, gpa, size, true);

	kvm_nested_s2_unmap(kvm, true);

	write_unlock(&kvm->mmu_lock);

}

arch/arm64/kvm/nested.c

+3 −3
Original line number Diff line number Diff line
@@ -634,7 +634,7 @@ static struct kvm_s2_mmu *get_s2_mmu_nested(struct kvm_vcpu *vcpu) 


	/* Clear the old state */

	if (kvm_s2_mmu_valid(s2_mmu))

		kvm_stage2_unmap_range(s2_mmu, 0, kvm_phys_size(s2_mmu));

		kvm_stage2_unmap_range(s2_mmu, 0, kvm_phys_size(s2_mmu), false);



	/*

	 * The virtual VMID (modulo CnP) will be used as a key when matching
@@ -745,7 +745,7 @@ void kvm_nested_s2_wp(struct kvm *kvm) 
	}

}



void kvm_nested_s2_unmap(struct kvm *kvm)

void kvm_nested_s2_unmap(struct kvm *kvm, bool may_block)

{

	int i;
@@ -755,7 +755,7 @@ void kvm_nested_s2_unmap(struct kvm *kvm) 
		struct kvm_s2_mmu *mmu = &kvm->arch.nested_mmus[i];



		if (kvm_s2_mmu_valid(mmu))

			kvm_stage2_unmap_range(mmu, 0, kvm_phys_size(mmu));

			kvm_stage2_unmap_range(mmu, 0, kvm_phys_size(mmu), may_block);

	}

}

arch/arm64/kvm/sys_regs.c

+3 −3
Original line number Diff line number Diff line
@@ -2937,7 +2937,7 @@ static bool handle_alle1is(struct kvm_vcpu *vcpu, struct sys_reg_params *p, 
	 * Drop all shadow S2s, resulting in S1/S2 TLBIs for each of the

	 * corresponding VMIDs.

	 */

	kvm_nested_s2_unmap(vcpu->kvm);

	kvm_nested_s2_unmap(vcpu->kvm, true);



	write_unlock(&vcpu->kvm->mmu_lock);
@@ -2989,7 +2989,7 @@ union tlbi_info { 
static void s2_mmu_unmap_range(struct kvm_s2_mmu *mmu,

			       const union tlbi_info *info)

{

	kvm_stage2_unmap_range(mmu, info->range.start, info->range.size);

	kvm_stage2_unmap_range(mmu, info->range.start, info->range.size, true);

}



static bool handle_vmalls12e1is(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
@@ -3084,7 +3084,7 @@ static void s2_mmu_unmap_ipa(struct kvm_s2_mmu *mmu, 
	max_size = compute_tlb_inval_range(mmu, info->ipa.addr);

	base_addr &= ~(max_size - 1);



	kvm_stage2_unmap_range(mmu, base_addr, max_size);

	kvm_stage2_unmap_range(mmu, base_addr, max_size, true);

}



static bool handle_ipas2e1is(struct kvm_vcpu *vcpu, struct sys_reg_params *p,