Commit dfaa973a authored by Ram Pai's avatar Ram Pai Committed by Paul Mackerras
Browse files

KVM: PPC: Book3S HV: In H_SVM_INIT_DONE, migrate remaining normal-GFNs to secure-GFNs 



The Ultravisor is expected to explicitly call H_SVM_PAGE_IN for all the
pages of the SVM before calling H_SVM_INIT_DONE. This causes a huge
delay in tranistioning the VM to SVM. The Ultravisor is only interested
in the pages that contain the kernel, initrd and other important data
structures. The rest contain throw-away content.

However if not all pages are requested by the Ultravisor, the Hypervisor
continues to consider the GFNs corresponding to the non-requested pages
as normal GFNs. This can lead to data-corruption and undefined behavior.

In H_SVM_INIT_DONE handler, move all the PFNs associated with the SVM's
GFNs to secure-PFNs. Skip the GFNs that are already Paged-in or Shared
or Paged-in followed by a Paged-out.

Reviewed-by: default avatarBharata B Rao <bharata@linux.ibm.com>
Signed-off-by: default avatarRam Pai <linuxram@us.ibm.com>
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
parent 651a6310

Documentation/powerpc/ultravisor.rst

+2 −0
Original line number Diff line number Diff line
@@ -934,6 +934,8 @@ Return values 
	* H_UNSUPPORTED		if called from the wrong context (e.g.

				from an SVM or before an H_SVM_INIT_START

				hypercall).

	* H_STATE		if the hypervisor could not successfully

                                transition the VM to Secure VM.



Description

~~~~~~~~~~~

arch/powerpc/kvm/book3s_hv_uvmem.c

+132 −22
Original line number Diff line number Diff line
@@ -93,6 +93,7 @@ 
#include <asm/ultravisor.h>

#include <asm/mman.h>

#include <asm/kvm_ppc.h>

#include <asm/kvm_book3s_uvmem.h>



static struct dev_pagemap kvmppc_uvmem_pgmap;

static unsigned long *kvmppc_uvmem_bitmap;
@@ -348,6 +349,41 @@ static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm, 
	return false;

}



/*

 * starting from *gfn search for the next available GFN that is not yet

 * transitioned to a secure GFN.  return the value of that GFN in *gfn.  If a

 * GFN is found, return true, else return false

 *

 * Must be called with kvm->arch.uvmem_lock  held.

 */

static bool kvmppc_next_nontransitioned_gfn(const struct kvm_memory_slot *memslot,

		struct kvm *kvm, unsigned long *gfn)

{

	struct kvmppc_uvmem_slot *p;

	bool ret = false;

	unsigned long i;



	list_for_each_entry(p, &kvm->arch.uvmem_pfns, list)

		if (*gfn >= p->base_pfn && *gfn < p->base_pfn + p->nr_pfns)

			break;

	if (!p)

		return ret;

	/*

	 * The code below assumes, one to one correspondence between

	 * kvmppc_uvmem_slot and memslot.

	 */

	for (i = *gfn; i < p->base_pfn + p->nr_pfns; i++) {

		unsigned long index = i - p->base_pfn;



		if (!(p->pfns[index] & KVMPPC_GFN_FLAG_MASK)) {

			*gfn = i;

			ret = true;

			break;

		}

	}

	return ret;

}



static int kvmppc_memslot_page_merge(struct kvm *kvm,

		const struct kvm_memory_slot *memslot, bool merge)

{
@@ -460,16 +496,6 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm) 
	return ret;

}



unsigned long kvmppc_h_svm_init_done(struct kvm *kvm)

{

	if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START))

		return H_UNSUPPORTED;



	kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_DONE;

	pr_info("LPID %d went secure\n", kvm->arch.lpid);

	return H_SUCCESS;

}



/*

 * Drop device pages that we maintain for the secure guest

 *
@@ -588,12 +614,14 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm) 
}



/*

 * Alloc a PFN from private device memory pool and copy page from normal

 * memory to secure memory using UV_PAGE_IN uvcall.

 * Alloc a PFN from private device memory pool. If @pagein is true,

 * copy page from normal memory to secure memory using UV_PAGE_IN uvcall.

 */

static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start,

static int kvmppc_svm_page_in(struct vm_area_struct *vma,

		unsigned long start,

		unsigned long end, unsigned long gpa, struct kvm *kvm,

		   unsigned long page_shift)

		unsigned long page_shift,

		bool pagein)

{

	unsigned long src_pfn, dst_pfn = 0;

	struct migrate_vma mig;
@@ -624,11 +652,16 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start, 
		goto out_finalize;

	}



	if (pagein) {

		pfn = *mig.src >> MIGRATE_PFN_SHIFT;

		spage = migrate_pfn_to_page(*mig.src);

	if (spage)

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

			   page_shift);

		if (spage) {

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

					gpa, 0, page_shift);

			if (ret)

				goto out_finalize;

		}

	}



	*mig.dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;

	migrate_vma_pages(&mig);
@@ -637,6 +670,80 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start, 
	return ret;

}



static int kvmppc_uv_migrate_mem_slot(struct kvm *kvm,

		const struct kvm_memory_slot *memslot)

{

	unsigned long gfn = memslot->base_gfn;

	struct vm_area_struct *vma;

	unsigned long start, end;

	int ret = 0;



	mmap_read_lock(kvm->mm);

	mutex_lock(&kvm->arch.uvmem_lock);

	while (kvmppc_next_nontransitioned_gfn(memslot, kvm, &gfn)) {

		ret = H_STATE;

		start = gfn_to_hva(kvm, gfn);

		if (kvm_is_error_hva(start))

			break;



		end = start + (1UL << PAGE_SHIFT);

		vma = find_vma_intersection(kvm->mm, start, end);

		if (!vma || vma->vm_start > start || vma->vm_end < end)

			break;



		ret = kvmppc_svm_page_in(vma, start, end,

				(gfn << PAGE_SHIFT), kvm, PAGE_SHIFT, false);

		if (ret) {

			ret = H_STATE;

			break;

		}



		/* relinquish the cpu if needed */

		cond_resched();

	}

	mutex_unlock(&kvm->arch.uvmem_lock);

	mmap_read_unlock(kvm->mm);

	return ret;

}



unsigned long kvmppc_h_svm_init_done(struct kvm *kvm)

{

	struct kvm_memslots *slots;

	struct kvm_memory_slot *memslot;

	int srcu_idx;

	long ret = H_SUCCESS;



	if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START))

		return H_UNSUPPORTED;



	/* migrate any unmoved normal pfn to device pfns*/

	srcu_idx = srcu_read_lock(&kvm->srcu);

	slots = kvm_memslots(kvm);

	kvm_for_each_memslot(memslot, slots) {

		ret = kvmppc_uv_migrate_mem_slot(kvm, memslot);

		if (ret) {

			/*

			 * The pages will remain transitioned.

			 * Its the callers responsibility to

			 * terminate the VM, which will undo

			 * all state of the VM. Till then

			 * this VM is in a erroneous state.

			 * Its KVMPPC_SECURE_INIT_DONE will

			 * remain unset.

			 */

			ret = H_STATE;

			goto out;

		}

	}



	kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_DONE;

	pr_info("LPID %d went secure\n", kvm->arch.lpid);



out:

	srcu_read_unlock(&kvm->srcu, srcu_idx);

	return ret;

}



/*

 * Shares the page with HV, thus making it a normal page.

 *
@@ -745,7 +852,10 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa, 
	if (!vma || vma->vm_start > start || vma->vm_end < end)

		goto out_unlock;



	if (!kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift))

	if (kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift,

				true))

		goto out_unlock;



	ret = H_SUCCESS;



out_unlock: