[v3 3/5] KVM: PPC: Book3S HV: migrate remaining normal-GFNs to secure-GFNs in H_SVM_INIT_DONE
Ram Pai
linuxram at us.ibm.com
Sat Jul 11 19:13:45 AEST 2020
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 interested in the pages that
contain the kernel, initrd and other important data structures. The rest of the
pages contain throw-away content. Hence requesting just the necessary and
sufficient pages from the Hypervisor is sufficient.
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.
Move all the PFNs associated with the SVM's GFNs to secure-PFNs, in
H_SVM_INIT_DONE. Skip the GFNs that are already Paged-in or Shared or
Paged-in followed by a Paged-out.
Cc: Paul Mackerras <paulus at ozlabs.org>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Bharata B Rao <bharata at linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>
Cc: Laurent Dufour <ldufour at linux.ibm.com>
Cc: Thiago Jung Bauermann <bauerman at linux.ibm.com>
Cc: David Gibson <david at gibson.dropbear.id.au>
Cc: Claudio Carvalho <cclaudio at linux.ibm.com>
Cc: kvm-ppc at vger.kernel.org
Cc: linuxppc-dev at lists.ozlabs.org
Signed-off-by: Ram Pai <linuxram at us.ibm.com>
---
Documentation/powerpc/ultravisor.rst | 2 +
arch/powerpc/include/asm/kvm_book3s_uvmem.h | 2 +
arch/powerpc/kvm/book3s_hv_uvmem.c | 166 +++++++++++++++++++++++++---
3 files changed, 156 insertions(+), 14 deletions(-)
diff --git a/Documentation/powerpc/ultravisor.rst b/Documentation/powerpc/ultravisor.rst
index df136c8..d98fc85 100644
--- a/Documentation/powerpc/ultravisor.rst
+++ b/Documentation/powerpc/ultravisor.rst
@@ -933,6 +933,8 @@ 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
~~~~~~~~~~~
diff --git a/arch/powerpc/include/asm/kvm_book3s_uvmem.h b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
index 9cb7d8b..f229ab5 100644
--- a/arch/powerpc/include/asm/kvm_book3s_uvmem.h
+++ b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
@@ -23,6 +23,8 @@ unsigned long kvmppc_h_svm_page_out(struct kvm *kvm,
unsigned long kvmppc_h_svm_init_abort(struct kvm *kvm);
void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
struct kvm *kvm, bool skip_page_out);
+int kvmppc_uv_migrate_mem_slot(struct kvm *kvm,
+ const struct kvm_memory_slot *memslot);
#else
static inline int kvmppc_uvmem_init(void)
{
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 6d6c256..12ed52a 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -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 +349,43 @@ 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
+ */
+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;
+
+ mutex_lock(&kvm->arch.uvmem_lock);
+
+ 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)
+ goto out;
+ /*
+ * 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;
+ }
+ }
+out:
+ mutex_unlock(&kvm->arch.uvmem_lock);
+ return ret;
+}
+
static int kvmppc_memslot_page_merge(struct kvm *kvm,
struct kvm_memory_slot *memslot, bool merge)
{
@@ -461,12 +499,31 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
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) {
+ ret = H_STATE;
+ goto out;
+ }
+ }
+
kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_DONE;
pr_info("LPID %d went secure\n", kvm->arch.lpid);
- return H_SUCCESS;
+
+out:
+ srcu_read_unlock(&kvm->srcu, srcu_idx);
+ return ret;
}
/*
@@ -587,12 +644,14 @@ 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,
- unsigned long end, unsigned long gpa, struct kvm *kvm,
- unsigned long page_shift)
+static int kvmppc_svm_migrate_page(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;
@@ -613,7 +672,7 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start,
return ret;
if (!(*mig.src & MIGRATE_PFN_MIGRATE)) {
- ret = -1;
+ ret = -2;
goto out_finalize;
}
@@ -623,11 +682,16 @@ 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 +701,77 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start,
}
/*
+ * return 1, if some page migration failed because of transient error,
+ * while the remaining pages migrated successfully.
+ * The caller can use this as a hint to retry.
+ *
+ * return 0 otherwise. *ret indicates the success status
+ * of this call.
+ */
+static int __kvmppc_uv_migrate_mem_slot(struct kvm *kvm,
+ const struct kvm_memory_slot *memslot, int *ret)
+{
+ unsigned long gfn = memslot->base_gfn;
+ struct vm_area_struct *vma;
+ unsigned long start, end;
+ bool retry = 0;
+
+ *ret = 0;
+ while (kvmppc_next_nontransitioned_gfn(memslot, kvm, &gfn)) {
+
+ down_write(&kvm->mm->mmap_sem);
+ start = gfn_to_hva(kvm, gfn);
+ if (kvm_is_error_hva(start)) {
+ *ret = H_STATE;
+ goto next;
+ }
+
+ end = start + (1UL << PAGE_SHIFT);
+ vma = find_vma_intersection(kvm->mm, start, end);
+ if (!vma || vma->vm_start > start || vma->vm_end < end) {
+ *ret = H_STATE;
+ goto next;
+ }
+
+ mutex_lock(&kvm->arch.uvmem_lock);
+ *ret = kvmppc_svm_migrate_page(vma, start, end,
+ (gfn << PAGE_SHIFT), kvm, PAGE_SHIFT, false);
+ mutex_unlock(&kvm->arch.uvmem_lock);
+
+next:
+ up_write(&kvm->mm->mmap_sem);
+
+ if (*ret == -2) {
+ retry = 1;
+ continue;
+ }
+
+ if (*ret)
+ return 0;
+ }
+ return retry;
+}
+
+#define REPEAT_COUNT 10
+
+int kvmppc_uv_migrate_mem_slot(struct kvm *kvm,
+ const struct kvm_memory_slot *memslot)
+{
+ int ret = 0, repeat_count = REPEAT_COUNT;
+
+ /*
+ * try migration of pages in the memslot 'repeat_count' number of
+ * times, provided each time migration fails because of transient
+ * errors only.
+ */
+ while (__kvmppc_uv_migrate_mem_slot(kvm, memslot, &ret) &&
+ repeat_count--)
+ ;
+
+ return ret;
+}
+
+/*
* Shares the page with HV, thus making it a normal page.
*
* - If the page is already secure, then provision a new page and share
@@ -740,8 +875,11 @@ 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_migrate_page(vma, start, end, gpa, kvm, page_shift,
+ true))
+ goto out_unlock;
+
+ ret = H_SUCCESS;
out_unlock:
mutex_unlock(&kvm->arch.uvmem_lock);
--
1.8.3.1
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