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    SubjectRe: [PATCH RFC v7 11/64] KVM: SEV: Support private pages in LAUNCH_UPDATE_DATA
    On Wed, Dec 14, 2022 at 01:40:03PM -0600, Michael Roth wrote:
    > From: Nikunj A Dadhania <nikunj@amd.com>
    >
    > Pre-boot guest payload needs to be encrypted and VMM has copied it
    > over to the private-fd. Add support to get the pfn from the memfile fd
    > for encrypting the payload in-place.
    >
    > Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
    > Signed-off-by: Michael Roth <michael.roth@amd.com>
    > ---
    > arch/x86/kvm/svm/sev.c | 79 ++++++++++++++++++++++++++++++++++--------
    > 1 file changed, 64 insertions(+), 15 deletions(-)
    >
    > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
    > index a7e4e3005786..ae4920aeb281 100644
    > --- a/arch/x86/kvm/svm/sev.c
    > +++ b/arch/x86/kvm/svm/sev.c
    > @@ -107,6 +107,11 @@ static inline bool is_mirroring_enc_context(struct kvm *kvm)
    > return !!to_kvm_svm(kvm)->sev_info.enc_context_owner;
    > }
    >
    > +static bool kvm_is_upm_enabled(struct kvm *kvm)
    > +{
    > + return kvm->arch.upm_mode;
    > +}
    > +
    > /* Must be called with the sev_bitmap_lock held */
    > static bool __sev_recycle_asids(int min_asid, int max_asid)
    > {
    > @@ -382,6 +387,38 @@ static int sev_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
    > return ret;
    > }
    >
    > +static int sev_get_memfile_pfn_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_restricted_mem_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_get_memfile_pfn(struct kvm *kvm, unsigned long addr,
    > + unsigned long size, unsigned long npages,
    > + struct page **pages)
    > +{
    > + return kvm_vm_do_hva_range_op(kvm, addr, size,
    > + sev_get_memfile_pfn_handler, pages);
    > +}
    > +
    > static struct page **sev_pin_memory(struct kvm *kvm, unsigned long uaddr,
    > unsigned long ulen, unsigned long *n,
    > int write)
    > @@ -424,16 +461,25 @@ static struct page **sev_pin_memory(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_is_upm_enabled(kvm)) {
    > + /* Get the PFN from memfile */
    > + if (sev_get_memfile_pfn(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;
    >
    > @@ -514,6 +560,7 @@ static int sev_launch_update_shared_gfn_handler(struct kvm *kvm,
    >
    > size = (range->end - range->start) << PAGE_SHIFT;
    > vaddr_end = vaddr + size;
    > + WARN_ON(size < PAGE_SIZE);
    >
    > /* Lock the user memory. */
    > inpages = sev_pin_memory(kvm, vaddr, size, &npages, 1);
    > @@ -554,13 +601,16 @@ static int sev_launch_update_shared_gfn_handler(struct kvm *kvm,
    > }
    >
    > e_unpin:
    > - /* content of memory is updated, mark pages dirty */
    > - for (i = 0; i < npages; i++) {
    > - set_page_dirty_lock(inpages[i]);
    > - mark_page_accessed(inpages[i]);
    > + if (!kvm_is_upm_enabled(kvm)) {
    > + /* content of memory is updated, mark pages dirty */
    > + for (i = 0; i < npages; i++) {
    > + set_page_dirty_lock(inpages[i]);
    > + mark_page_accessed(inpages[i]);
    > + }
    > + /* unlock the user pages */
    > + sev_unpin_memory(kvm, inpages, npages);
    > }
    > - /* unlock the user pages */
    > - sev_unpin_memory(kvm, inpages, npages);
    > +
    > return ret;
    > }
    >
    > @@ -609,9 +659,8 @@ static int sev_launch_update_priv_gfn_handler(struct kvm *kvm,
    > goto e_ret;
    > kvm_release_pfn_clean(pfn);
    > }
    > - kvm_vm_set_region_attr(kvm, range->start, range->end,
    > - true /* priv_attr */);
    >
    > + kvm_vm_set_region_attr(kvm, range->start, range->end, KVM_MEMORY_ATTRIBUTE_PRIVATE);
    > e_ret:
    > return ret;
    > }
    > --
    > 2.25.1
    >

    kvm_vm_set_region_attr() should be fixed already in:

    https://lore.kernel.org/all/20221214194056.161492-11-michael.roth@amd.com/

    BR, Jarkko

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