KVM: arm64: Drop pkvm_mem_transition for host/hyp sharing

Simplify the __pkvm_host_{un}share_hyp() paths by not using the
pkvm_mem_transition machinery. As there are the last users of the
do_share()/do_unshare(), remove all the now-unused code as well.

No functional changes intended.

Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20250110121936.1559655-3-qperret@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 3a3d9fcbc5084e81aa2792b3f45b8cb72fa7661c..cd8d233b95273b9dd5319fd6e8f4f4e7bf91b742 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -685,36 +685,6 @@ static int host_request_owned_transition(u64 *completer_addr,
        return __host_check_page_state_range(addr, size, PKVM_PAGE_OWNED);
 }
 
-static int host_request_unshare(u64 *completer_addr,
-                               const struct pkvm_mem_transition *tx)
-{
-       u64 size = tx->nr_pages * PAGE_SIZE;
-       u64 addr = tx->initiator.addr;
-
-       *completer_addr = tx->initiator.host.completer_addr;
-       return __host_check_page_state_range(addr, size, PKVM_PAGE_SHARED_OWNED);
-}
-
-static int host_initiate_share(u64 *completer_addr,
-                              const struct pkvm_mem_transition *tx)
-{
-       u64 size = tx->nr_pages * PAGE_SIZE;
-       u64 addr = tx->initiator.addr;
-
-       *completer_addr = tx->initiator.host.completer_addr;
-       return __host_set_page_state_range(addr, size, PKVM_PAGE_SHARED_OWNED);
-}
-
-static int host_initiate_unshare(u64 *completer_addr,
-                                const struct pkvm_mem_transition *tx)
-{
-       u64 size = tx->nr_pages * PAGE_SIZE;
-       u64 addr = tx->initiator.addr;
-
-       *completer_addr = tx->initiator.host.completer_addr;
-       return __host_set_page_state_range(addr, size, PKVM_PAGE_OWNED);
-}
-
 static int host_initiate_donation(u64 *completer_addr,
                                  const struct pkvm_mem_transition *tx)
 {
@@ -802,31 +772,6 @@ static bool __hyp_ack_skip_pgtable_check(const struct pkvm_mem_transition *tx)
                 tx->initiator.id != PKVM_ID_HOST);
 }
 
-static int hyp_ack_share(u64 addr, const struct pkvm_mem_transition *tx,
-                        enum kvm_pgtable_prot perms)
-{
-       u64 size = tx->nr_pages * PAGE_SIZE;
-
-       if (perms != PAGE_HYP)
-               return -EPERM;
-
-       if (__hyp_ack_skip_pgtable_check(tx))
-               return 0;
-
-       return __hyp_check_page_state_range(addr, size, PKVM_NOPAGE);
-}
-
-static int hyp_ack_unshare(u64 addr, const struct pkvm_mem_transition *tx)
-{
-       u64 size = tx->nr_pages * PAGE_SIZE;
-
-       if (tx->initiator.id == PKVM_ID_HOST && hyp_page_count((void *)addr))
-               return -EBUSY;
-
-       return __hyp_check_page_state_range(addr, size,
-                                           PKVM_PAGE_SHARED_BORROWED);
-}
-
 static int hyp_ack_donation(u64 addr, const struct pkvm_mem_transition *tx)
 {
        u64 size = tx->nr_pages * PAGE_SIZE;
@@ -837,24 +782,6 @@ static int hyp_ack_donation(u64 addr, const struct pkvm_mem_transition *tx)
        return __hyp_check_page_state_range(addr, size, PKVM_NOPAGE);
 }
 
-static int hyp_complete_share(u64 addr, const struct pkvm_mem_transition *tx,
-                             enum kvm_pgtable_prot perms)
-{
-       void *start = (void *)addr, *end = start + (tx->nr_pages * PAGE_SIZE);
-       enum kvm_pgtable_prot prot;
-
-       prot = pkvm_mkstate(perms, PKVM_PAGE_SHARED_BORROWED);
-       return pkvm_create_mappings_locked(start, end, prot);
-}
-
-static int hyp_complete_unshare(u64 addr, const struct pkvm_mem_transition *tx)
-{
-       u64 size = tx->nr_pages * PAGE_SIZE;
-       int ret = kvm_pgtable_hyp_unmap(&pkvm_pgtable, addr, size);
-
-       return (ret != size) ? -EFAULT : 0;
-}
-
 static int hyp_complete_donation(u64 addr,
                                 const struct pkvm_mem_transition *tx)
 {
@@ -885,180 +812,6 @@ static int __guest_check_page_state_range(struct pkvm_hyp_vcpu *vcpu, u64 addr,
        return check_page_state_range(&vm->pgt, addr, size, &d);
 }
 
-static int check_share(struct pkvm_mem_share *share)
-{
-       const struct pkvm_mem_transition *tx = &share->tx;
-       u64 completer_addr;
-       int ret;
-
-       switch (tx->initiator.id) {
-       case PKVM_ID_HOST:
-               ret = host_request_owned_transition(&completer_addr, tx);
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       if (ret)
-               return ret;
-
-       switch (tx->completer.id) {
-       case PKVM_ID_HYP:
-               ret = hyp_ack_share(completer_addr, tx, share->completer_prot);
-               break;
-       case PKVM_ID_FFA:
-               /*
-                * We only check the host; the secure side will check the other
-                * end when we forward the FFA call.
-                */
-               ret = 0;
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       return ret;
-}
-
-static int __do_share(struct pkvm_mem_share *share)
-{
-       const struct pkvm_mem_transition *tx = &share->tx;
-       u64 completer_addr;
-       int ret;
-
-       switch (tx->initiator.id) {
-       case PKVM_ID_HOST:
-               ret = host_initiate_share(&completer_addr, tx);
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       if (ret)
-               return ret;
-
-       switch (tx->completer.id) {
-       case PKVM_ID_HYP:
-               ret = hyp_complete_share(completer_addr, tx, share->completer_prot);
-               break;
-       case PKVM_ID_FFA:
-               /*
-                * We're not responsible for any secure page-tables, so there's
-                * nothing to do here.
-                */
-               ret = 0;
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       return ret;
-}
-
-/*
- * do_share():
- *
- * The page owner grants access to another component with a given set
- * of permissions.
- *
- * Initiator: OWNED    => SHARED_OWNED
- * Completer: NOPAGE   => SHARED_BORROWED
- */
-static int do_share(struct pkvm_mem_share *share)
-{
-       int ret;
-
-       ret = check_share(share);
-       if (ret)
-               return ret;
-
-       return WARN_ON(__do_share(share));
-}
-
-static int check_unshare(struct pkvm_mem_share *share)
-{
-       const struct pkvm_mem_transition *tx = &share->tx;
-       u64 completer_addr;
-       int ret;
-
-       switch (tx->initiator.id) {
-       case PKVM_ID_HOST:
-               ret = host_request_unshare(&completer_addr, tx);
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       if (ret)
-               return ret;
-
-       switch (tx->completer.id) {
-       case PKVM_ID_HYP:
-               ret = hyp_ack_unshare(completer_addr, tx);
-               break;
-       case PKVM_ID_FFA:
-               /* See check_share() */
-               ret = 0;
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       return ret;
-}
-
-static int __do_unshare(struct pkvm_mem_share *share)
-{
-       const struct pkvm_mem_transition *tx = &share->tx;
-       u64 completer_addr;
-       int ret;
-
-       switch (tx->initiator.id) {
-       case PKVM_ID_HOST:
-               ret = host_initiate_unshare(&completer_addr, tx);
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       if (ret)
-               return ret;
-
-       switch (tx->completer.id) {
-       case PKVM_ID_HYP:
-               ret = hyp_complete_unshare(completer_addr, tx);
-               break;
-       case PKVM_ID_FFA:
-               /* See __do_share() */
-               ret = 0;
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       return ret;
-}
-
-/*
- * do_unshare():
- *
- * The page owner revokes access from another component for a range of
- * pages which were previously shared using do_share().
- *
- * Initiator: SHARED_OWNED     => OWNED
- * Completer: SHARED_BORROWED  => NOPAGE
- */
-static int do_unshare(struct pkvm_mem_share *share)
-{
-       int ret;
-
-       ret = check_unshare(share);
-       if (ret)
-               return ret;
-
-       return WARN_ON(__do_unshare(share));
-}
-
 static int check_donation(struct pkvm_mem_donation *donation)
 {
        const struct pkvm_mem_transition *tx = &donation->tx;
@@ -1149,31 +902,29 @@ static int do_donate(struct pkvm_mem_donation *donation)
 
 int __pkvm_host_share_hyp(u64 pfn)
 {
+       u64 phys = hyp_pfn_to_phys(pfn);
+       void *virt = __hyp_va(phys);
+       enum kvm_pgtable_prot prot;
+       u64 size = PAGE_SIZE;
        int ret;
-       u64 host_addr = hyp_pfn_to_phys(pfn);
-       u64 hyp_addr = (u64)__hyp_va(host_addr);
-       struct pkvm_mem_share share = {
-               .tx     = {
-                       .nr_pages       = 1,
-                       .initiator      = {
-                               .id     = PKVM_ID_HOST,
-                               .addr   = host_addr,
-                               .host   = {
-                                       .completer_addr = hyp_addr,
-                               },
-                       },
-                       .completer      = {
-                               .id     = PKVM_ID_HYP,
-                       },
-               },
-               .completer_prot = PAGE_HYP,
-       };
 
        host_lock_component();
        hyp_lock_component();
 
-       ret = do_share(&share);
+       ret = __host_check_page_state_range(phys, size, PKVM_PAGE_OWNED);
+       if (ret)
+               goto unlock;
+       if (IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) {
+               ret = __hyp_check_page_state_range((u64)virt, size, PKVM_NOPAGE);
+               if (ret)
+                       goto unlock;
+       }
+
+       prot = pkvm_mkstate(PAGE_HYP, PKVM_PAGE_SHARED_BORROWED);
+       WARN_ON(pkvm_create_mappings_locked(virt, virt + size, prot));
+       WARN_ON(__host_set_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED));
 
+unlock:
        hyp_unlock_component();
        host_unlock_component();
 
@@ -1182,31 +933,29 @@ int __pkvm_host_share_hyp(u64 pfn)
 
 int __pkvm_host_unshare_hyp(u64 pfn)
 {
+       u64 phys = hyp_pfn_to_phys(pfn);
+       u64 virt = (u64)__hyp_va(phys);
+       u64 size = PAGE_SIZE;
        int ret;
-       u64 host_addr = hyp_pfn_to_phys(pfn);
-       u64 hyp_addr = (u64)__hyp_va(host_addr);
-       struct pkvm_mem_share share = {
-               .tx     = {
-                       .nr_pages       = 1,
-                       .initiator      = {
-                               .id     = PKVM_ID_HOST,
-                               .addr   = host_addr,
-                               .host   = {
-                                       .completer_addr = hyp_addr,
-                               },
-                       },
-                       .completer      = {
-                               .id     = PKVM_ID_HYP,
-                       },
-               },
-               .completer_prot = PAGE_HYP,
-       };
 
        host_lock_component();
        hyp_lock_component();
 
-       ret = do_unshare(&share);
+       ret = __host_check_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED);
+       if (ret)
+               goto unlock;
+       ret = __hyp_check_page_state_range(virt, size, PKVM_PAGE_SHARED_BORROWED);
+       if (ret)
+               goto unlock;
+       if (hyp_page_count((void *)virt)) {
+               ret = -EBUSY;
+               goto unlock;
+       }
+
+       WARN_ON(kvm_pgtable_hyp_unmap(&pkvm_pgtable, virt, size) != size);
+       WARN_ON(__host_set_page_state_range(phys, size, PKVM_PAGE_OWNED));
 
+unlock:
        hyp_unlock_component();
        host_unlock_component();