From: Nikunj A Dadhania <[email protected]>
Do not pin the guest memory backed by a restrictedmem backend, as
pages in the restrictedmem are already pinned. Instead, populate the
pages array for these guests using the already-pinned pages provided by
restrictedmem backend.
Signed-off-by: Nikunj A Dadhania <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
---
arch/x86/kvm/svm/sev.c | 68 +++++++++++++++++++++++++++++++++++-------
1 file changed, 58 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 523c78bbff3f..ad9b29ff4590 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -383,9 +383,46 @@ static int sev_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
return ret;
}
+static int sev_private_mem_get_pages_handler(struct kvm *kvm, struct kvm_gfn_range *range,
+ void *data)
+{
+ struct kvm_memory_slot *memslot = range->slot;
+ struct page **pages = data;
+ int ret = 0, i = 0;
+ kvm_pfn_t pfn;
+ gfn_t gfn;
+
+ for (gfn = range->start; gfn < range->end; gfn++) {
+ int order;
+
+ ret = kvm_restrictedmem_get_pfn(memslot, gfn, &pfn, &order);
+ if (ret)
+ return ret;
+
+ if (is_error_noslot_pfn(pfn))
+ return -EFAULT;
+
+ pages[i++] = pfn_to_page(pfn);
+ }
+
+ return ret;
+}
+
+static int sev_private_mem_get_pages(struct kvm *kvm, unsigned long addr,
+ unsigned long size, unsigned long npages,
+ struct page **pages)
+{
+ return kvm_vm_do_hva_range_op(kvm, addr, addr + size,
+ sev_private_mem_get_pages_handler, pages);
+}
+
/*
* Legacy SEV guest pin the pages and return the array populated with pinned
* pages.
+ *
+ * SEV guests using restricted memfd backend, pages are already marked as
+ * unmovable and unevictable. Populate the pages array for these guests using
+ * restrictedmem get_pfn.
*/
static struct page **sev_memory_get_pages(struct kvm *kvm, unsigned long uaddr,
unsigned long ulen, unsigned long *n,
@@ -393,7 +430,7 @@ static struct page **sev_memory_get_pages(struct kvm *kvm, unsigned long uaddr,
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
unsigned long npages, size;
- int npinned;
+ int npinned = 0;
unsigned long locked, lock_limit;
struct page **pages;
unsigned long first, last;
@@ -429,16 +466,25 @@ static struct page **sev_memory_get_pages(struct kvm *kvm, unsigned long uaddr,
if (!pages)
return ERR_PTR(-ENOMEM);
- /* Pin the user virtual address. */
- npinned = pin_user_pages_fast(uaddr, npages, write ? FOLL_WRITE : 0, pages);
- if (npinned != npages) {
- pr_err("SEV: Failure locking %lu pages.\n", npages);
- ret = -ENOMEM;
- goto err;
+ if (kvm_arch_has_private_mem(kvm)) {
+ /* Get the PFN from memfile */
+ if (sev_private_mem_get_pages(kvm, uaddr, ulen, npages, pages)) {
+ pr_err("%s: ERROR: unable to find slot for uaddr %lx", __func__, uaddr);
+ ret = -ENOMEM;
+ goto err;
+ }
+ } else {
+ /* Pin the user virtual address. */
+ npinned = pin_user_pages_fast(uaddr, npages, write ? FOLL_WRITE : 0, pages);
+ if (npinned != npages) {
+ pr_err("SEV: Failure locking %lu pages.\n", npages);
+ ret = -ENOMEM;
+ goto err;
+ }
+ sev->pages_locked = locked;
}
*n = npages;
- sev->pages_locked = locked;
return pages;
@@ -455,9 +501,11 @@ static void sev_memory_put_pages(struct kvm *kvm, struct page **pages,
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
- unpin_user_pages(pages, npages);
+ if (!kvm_arch_has_private_mem(kvm)) {
+ unpin_user_pages(pages, npages);
+ sev->pages_locked -= npages;
+ }
kvfree(pages);
- sev->pages_locked -= npages;
}
static void sev_clflush_pages(struct page *pages[], unsigned long npages)
--
2.25.1
On 2/20/23 19:38, Michael Roth wrote:
> From: Nikunj A Dadhania <[email protected]>
>
> Do not pin the guest memory backed by a restrictedmem backend, as
> pages in the restrictedmem are already pinned. Instead, populate the
> pages array for these guests using the already-pinned pages provided by
IIUC the "already pinned" became "effectively unmovable and unevictable"
since the earlier versions, so that would be more accurate now?
> +static int sev_private_mem_get_pages(struct kvm *kvm, unsigned long addr,
> + unsigned long size, unsigned long npages,
> + struct page **pages)
> +{
> + return kvm_vm_do_hva_range_op(kvm, addr, addr + size,
> + sev_private_mem_get_pages_handler, pages);
> +}
> +
> /*
> * Legacy SEV guest pin the pages and return the array populated with pinned
> * pages.
> + *
> + * SEV guests using restricted memfd backend, pages are already marked as
> + * unmovable and unevictable. Populate the pages array for these guests using
> + * restrictedmem get_pfn.
Right.
On 03/03/23 19:35, Vlastimil Babka wrote:
> On 2/20/23 19:38, Michael Roth wrote:
>> From: Nikunj A Dadhania <[email protected]>
>>
>> Do not pin the guest memory backed by a restrictedmem backend, as
>> pages in the restrictedmem are already pinned. Instead, populate the
>> pages array for these guests using the already-pinned pages provided by
>
> IIUC the "already pinned" became "effectively unmovable and unevictable"
> since the earlier versions, so that would be more accurate now?
Yes, that makes sense.
Regards
Nikunj