Commit 040537ce authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: PPC: Explicitly require struct page memory for Ultravisor sharing 



Explicitly require "struct page" memory when sharing memory between
guest and host via an Ultravisor.  Given the number of pfn_to_page()
calls in the code, it's safe to assume that KVM already requires that the
pfn returned by gfn_to_pfn() is backed by struct page, i.e. this is
likely a bug fix, not a reduction in KVM capabilities.

Switching to gfn_to_page() will eventually allow removing gfn_to_pfn()
and kvm_pfn_to_refcounted_page().

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Tested-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-79-seanjc@google.com>
parent 570d666c

arch/powerpc/kvm/book3s_hv_uvmem.c

+12 −13
Original line number Diff line number Diff line
@@ -879,9 +879,8 @@ static unsigned long kvmppc_share_page(struct kvm *kvm, unsigned long gpa, 
{



	int ret = H_PARAMETER;

	struct page *uvmem_page;

	struct page *page, *uvmem_page;

	struct kvmppc_uvmem_page_pvt *pvt;

	unsigned long pfn;

	unsigned long gfn = gpa >> page_shift;

	int srcu_idx;

	unsigned long uvmem_pfn;
@@ -901,8 +900,8 @@ static unsigned long kvmppc_share_page(struct kvm *kvm, unsigned long gpa, 


retry:

	mutex_unlock(&kvm->arch.uvmem_lock);

	pfn = gfn_to_pfn(kvm, gfn);

	if (is_error_noslot_pfn(pfn))

	page = gfn_to_page(kvm, gfn);

	if (!page)

		goto out;



	mutex_lock(&kvm->arch.uvmem_lock);
@@ -911,16 +910,16 @@ static unsigned long kvmppc_share_page(struct kvm *kvm, unsigned long gpa, 
		pvt = uvmem_page->zone_device_data;

		pvt->skip_page_out = true;

		pvt->remove_gfn = false; /* it continues to be a valid GFN */

		kvm_release_pfn_clean(pfn);

		kvm_release_page_unused(page);

		goto retry;

	}



	if (!uv_page_in(kvm->arch.lpid, pfn << page_shift, gpa, 0,

	if (!uv_page_in(kvm->arch.lpid, page_to_pfn(page) << page_shift, gpa, 0,

				page_shift)) {

		kvmppc_gfn_shared(gfn, kvm);

		ret = H_SUCCESS;

	}

	kvm_release_pfn_clean(pfn);

	kvm_release_page_clean(page);

	mutex_unlock(&kvm->arch.uvmem_lock);

out:

	srcu_read_unlock(&kvm->srcu, srcu_idx);
@@ -1083,21 +1082,21 @@ kvmppc_h_svm_page_out(struct kvm *kvm, unsigned long gpa, 


int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn)

{

	unsigned long pfn;

	struct page *page;

	int ret = U_SUCCESS;



	pfn = gfn_to_pfn(kvm, gfn);

	if (is_error_noslot_pfn(pfn))

	page = gfn_to_page(kvm, gfn);

	if (!page)

		return -EFAULT;



	mutex_lock(&kvm->arch.uvmem_lock);

	if (kvmppc_gfn_is_uvmem_pfn(gfn, kvm, NULL))

		goto out;



	ret = uv_page_in(kvm->arch.lpid, pfn << PAGE_SHIFT, gfn << PAGE_SHIFT,

			 0, PAGE_SHIFT);

	ret = uv_page_in(kvm->arch.lpid, page_to_pfn(page) << PAGE_SHIFT,

			 gfn << PAGE_SHIFT, 0, PAGE_SHIFT);

out:

	kvm_release_pfn_clean(pfn);

	kvm_release_page_clean(page);

	mutex_unlock(&kvm->arch.uvmem_lock);

	return (ret == U_SUCCESS) ? RESUME_GUEST : -EFAULT;

}