Commit bf4bea8e authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Marc Zyngier
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kvm: fix kvm_is_mmio_pfn() and rename to kvm_is_reserved_pfn() 



This reverts commit 85c8555f ("KVM: check for !is_zero_pfn() in
kvm_is_mmio_pfn()") and renames the function to kvm_is_reserved_pfn.

The problem being addressed by the patch above was that some ARM code
based the memory mapping attributes of a pfn on the return value of
kvm_is_mmio_pfn(), whose name indeed suggests that such pfns should
be mapped as device memory.

However, kvm_is_mmio_pfn() doesn't do quite what it says on the tin,
and the existing non-ARM users were already using it in a way which
suggests that its name should probably have been 'kvm_is_reserved_pfn'
from the beginning, e.g., whether or not to call get_page/put_page on
it etc. This means that returning false for the zero page is a mistake
and the patch above should be reverted.

Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent 07a9748c

arch/ia64/kvm/kvm-ia64.c

+1 −1
Original line number Diff line number Diff line
@@ -1563,7 +1563,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, 


	for (i = 0; i < npages; i++) {

		pfn = gfn_to_pfn(kvm, base_gfn + i);

		if (!kvm_is_mmio_pfn(pfn)) {

		if (!kvm_is_reserved_pfn(pfn)) {

			kvm_set_pmt_entry(kvm, base_gfn + i,

					pfn << PAGE_SHIFT,

				_PAGE_AR_RWX | _PAGE_MA_WB);

arch/x86/kvm/mmu.c

+3 −3
Original line number Diff line number Diff line
@@ -630,7 +630,7 @@ static int mmu_spte_clear_track_bits(u64 *sptep) 
	 * kvm mmu, before reclaiming the page, we should

	 * unmap it from mmu first.

	 */

	WARN_ON(!kvm_is_mmio_pfn(pfn) && !page_count(pfn_to_page(pfn)));

	WARN_ON(!kvm_is_reserved_pfn(pfn) && !page_count(pfn_to_page(pfn)));



	if (!shadow_accessed_mask || old_spte & shadow_accessed_mask)

		kvm_set_pfn_accessed(pfn);
@@ -2461,7 +2461,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, 
		spte |= PT_PAGE_SIZE_MASK;

	if (tdp_enabled)

		spte |= kvm_x86_ops->get_mt_mask(vcpu, gfn,

			kvm_is_mmio_pfn(pfn));

			kvm_is_reserved_pfn(pfn));



	if (host_writable)

		spte |= SPTE_HOST_WRITEABLE;
@@ -2737,7 +2737,7 @@ static void transparent_hugepage_adjust(struct kvm_vcpu *vcpu, 
	 * PT_PAGE_TABLE_LEVEL and there would be no adjustment done

	 * here.

	 */

	if (!is_error_noslot_pfn(pfn) && !kvm_is_mmio_pfn(pfn) &&

	if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn) &&

	    level == PT_PAGE_TABLE_LEVEL &&

	    PageTransCompound(pfn_to_page(pfn)) &&

	    !has_wrprotected_page(vcpu->kvm, gfn, PT_DIRECTORY_LEVEL)) {

include/linux/kvm_host.h

+1 −1
Original line number Diff line number Diff line
@@ -703,7 +703,7 @@ void kvm_arch_sync_events(struct kvm *kvm); 
int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu);

void kvm_vcpu_kick(struct kvm_vcpu *vcpu);



bool kvm_is_mmio_pfn(pfn_t pfn);

bool kvm_is_reserved_pfn(pfn_t pfn);



struct kvm_irq_ack_notifier {

	struct hlist_node link;

virt/kvm/kvm_main.c

+8 −8
Original line number Diff line number Diff line
@@ -107,10 +107,10 @@ EXPORT_SYMBOL_GPL(kvm_rebooting); 


static bool largepages_enabled = true;



bool kvm_is_mmio_pfn(pfn_t pfn)

bool kvm_is_reserved_pfn(pfn_t pfn)

{

	if (pfn_valid(pfn))

		return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn));

		return PageReserved(pfn_to_page(pfn));



	return true;

}
@@ -1321,7 +1321,7 @@ static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, 
	else if ((vma->vm_flags & VM_PFNMAP)) {

		pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) +

			vma->vm_pgoff;

		BUG_ON(!kvm_is_mmio_pfn(pfn));

		BUG_ON(!kvm_is_reserved_pfn(pfn));

	} else {

		if (async && vma_is_valid(vma, write_fault))

			*async = true;
@@ -1427,7 +1427,7 @@ static struct page *kvm_pfn_to_page(pfn_t pfn) 
	if (is_error_noslot_pfn(pfn))

		return KVM_ERR_PTR_BAD_PAGE;



	if (kvm_is_mmio_pfn(pfn)) {

	if (kvm_is_reserved_pfn(pfn)) {

		WARN_ON(1);

		return KVM_ERR_PTR_BAD_PAGE;

	}
@@ -1456,7 +1456,7 @@ EXPORT_SYMBOL_GPL(kvm_release_page_clean); 


void kvm_release_pfn_clean(pfn_t pfn)

{

	if (!is_error_noslot_pfn(pfn) && !kvm_is_mmio_pfn(pfn))

	if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn))

		put_page(pfn_to_page(pfn));

}

EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);
@@ -1477,7 +1477,7 @@ static void kvm_release_pfn_dirty(pfn_t pfn) 


void kvm_set_pfn_dirty(pfn_t pfn)

{

	if (!kvm_is_mmio_pfn(pfn)) {

	if (!kvm_is_reserved_pfn(pfn)) {

		struct page *page = pfn_to_page(pfn);

		if (!PageReserved(page))

			SetPageDirty(page);
@@ -1487,14 +1487,14 @@ EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty); 


void kvm_set_pfn_accessed(pfn_t pfn)

{

	if (!kvm_is_mmio_pfn(pfn))

	if (!kvm_is_reserved_pfn(pfn))

		mark_page_accessed(pfn_to_page(pfn));

}

EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed);



void kvm_get_pfn(pfn_t pfn)

{

	if (!kvm_is_mmio_pfn(pfn))

	if (!kvm_is_reserved_pfn(pfn))

		get_page(pfn_to_page(pfn));

}

EXPORT_SYMBOL_GPL(kvm_get_pfn);

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