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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: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Ram Pai 2020-07-27 11:07:17 -07:00 committed by Paul Mackerras
parent 651a631011
commit dfaa973ae9
2 changed files with 134 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/powerpc/ultravisor.rst
View File

@ -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
~~~~~~~~~~~

154
arch/powerpc/kvm/book3s_hv_uvmem.c
View File

@ -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 @@ out:
}
/*
* 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,
unsigned long end, unsigned long gpa, struct kvm *kvm,
unsigned long page_shift)
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,
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;
}
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 (pagein) {
pfn = *mig.src >> MIGRATE_PFN_SHIFT;
spage = migrate_pfn_to_page(*mig.src);
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 @@ out_finalize:
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.
*
@ -745,8 +852,11 @@ 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))
ret = H_SUCCESS;
if (kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift,
true))
goto out_unlock;
ret = H_SUCCESS;
out_unlock:
mutex_unlock(&kvm->arch.uvmem_lock);