Commit 08abf09f authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: Restrict the scope of the 'writable' attribute 



The 'writable' field is ambiguous, and indicates multiple things:

- whether the underlying memslot is writable

- whether we are resolving the fault with writable attributes

Add a new field to kvm_s2_fault_vma_info (map_writable) to indicate
the former condition, and have local writable variables to track
the latter.

Tested-by: default avatarFuad Tabba <tabba@google.com>
Reviewed-by: default avatarFuad Tabba <tabba@google.com>
Reviewed-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 18e13128

arch/arm64/kvm/mmu.c

+9 −7
Original line number Diff line number Diff line
@@ -1653,6 +1653,7 @@ struct kvm_s2_fault_vma_info { 
	gfn_t		gfn;

	bool		mte_allowed;

	bool		is_vma_cacheable;

	bool		map_writable;

};



static short kvm_s2_resolve_vma_size(const struct kvm_s2_fault_desc *s2fd,
@@ -1718,7 +1719,6 @@ static short kvm_s2_resolve_vma_size(const struct kvm_s2_fault_desc *s2fd, 
}



struct kvm_s2_fault {

	bool writable;

	bool s2_force_noncacheable;

	kvm_pfn_t pfn;

	bool force_pte;
@@ -1799,7 +1799,7 @@ static int kvm_s2_fault_pin_pfn(const struct kvm_s2_fault_desc *s2fd, 


	fault->pfn = __kvm_faultin_pfn(s2fd->memslot, get_canonical_gfn(s2fd, s2vi),

				       kvm_is_write_fault(s2fd->vcpu) ? FOLL_WRITE : 0,

				       &fault->writable, &fault->page);

				       &s2vi->map_writable, &fault->page);

	if (unlikely(is_error_noslot_pfn(fault->pfn))) {

		if (fault->pfn == KVM_PFN_ERR_HWPOISON) {

			kvm_send_hwpoison_signal(s2fd->hva, __ffs(s2vi->vma_pagesize));
@@ -1816,6 +1816,7 @@ static int kvm_s2_fault_compute_prot(const struct kvm_s2_fault_desc *s2fd, 
				     const struct kvm_s2_fault_vma_info *s2vi)

{

	struct kvm *kvm = s2fd->vcpu->kvm;

	bool writable = s2vi->map_writable;



	/*

	 * Check if this is non-struct page memory PFN, and cannot support
@@ -1855,7 +1856,7 @@ static int kvm_s2_fault_compute_prot(const struct kvm_s2_fault_desc *s2fd, 
		 * Only actually map the page as writable if this was a write

		 * fault.

		 */

		fault->writable = false;

		writable = false;

	}



	if (kvm_vcpu_trap_is_exec_fault(s2fd->vcpu) && fault->s2_force_noncacheable)
@@ -1873,9 +1874,9 @@ static int kvm_s2_fault_compute_prot(const struct kvm_s2_fault_desc *s2fd, 
	}



	if (s2fd->nested)

		adjust_nested_fault_perms(s2fd->nested, &fault->prot, &fault->writable);

		adjust_nested_fault_perms(s2fd->nested, &fault->prot, &writable);



	if (fault->writable)

	if (writable)

		fault->prot |= KVM_PGTABLE_PROT_W;



	if (kvm_vcpu_trap_is_exec_fault(s2fd->vcpu))
@@ -1904,6 +1905,7 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, 
			    const struct kvm_s2_fault_vma_info *s2vi, void *memcache)

{

	enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_SHARED;

	bool writable = fault->prot & KVM_PGTABLE_PROT_W;

	struct kvm *kvm = s2fd->vcpu->kvm;

	struct kvm_pgtable *pgt;

	long perm_fault_granule;
@@ -1964,7 +1966,7 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, 
	}



out_unlock:

	kvm_release_faultin_page(kvm, fault->page, !!ret, fault->writable);

	kvm_release_faultin_page(kvm, fault->page, !!ret, writable);

	kvm_fault_unlock(kvm);



	/*
@@ -1972,7 +1974,7 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, 
	 * making sure we adjust the canonical IPA if the mapping size has

	 * been updated (via a THP upgrade, for example).

	 */

	if (fault->writable && !ret) {

	if (writable && !ret) {

		phys_addr_t ipa = gfn_to_gpa(get_canonical_gfn(s2fd, s2vi));

		ipa &= ~(mapping_size - 1);

		mark_page_dirty_in_slot(kvm, s2fd->memslot, gpa_to_gfn(ipa));