KVM: arm64: Drop pkvm_mem_transition for host/hyp donations

Simplify the __pkvm_host_donate_hyp() and pkvm_hyp_donate_host() paths
by not using the pkvm_mem_transition machinery. As the last users of
this, also remove all the now unused code.

No functional changes intended.

Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20250110121936.1559655-4-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 cd8d233b95273b9dd5319fd6e8f4f4e7bf91b742..7ad7b133b81a86cce5e75172fcb2abb4faffe4ae 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -583,39 +583,6 @@ void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
        BUG_ON(ret && ret != -EAGAIN);
 }
 
-struct pkvm_mem_transition {
-       u64                             nr_pages;
-
-       struct {
-               enum pkvm_component_id  id;
-               /* Address in the initiator's address space */
-               u64                     addr;
-
-               union {
-                       struct {
-                               /* Address in the completer's address space */
-                               u64     completer_addr;
-                       } host;
-                       struct {
-                               u64     completer_addr;
-                       } hyp;
-               };
-       } initiator;
-
-       struct {
-               enum pkvm_component_id  id;
-       } completer;
-};
-
-struct pkvm_mem_share {
-       const struct pkvm_mem_transition        tx;
-       const enum kvm_pgtable_prot             completer_prot;
-};
-
-struct pkvm_mem_donation {
-       const struct pkvm_mem_transition        tx;
-};
-
 struct check_walk_data {
        enum pkvm_page_state    desired;
        enum pkvm_page_state    (*get_page_state)(kvm_pte_t pte, u64 addr);
@@ -675,56 +642,6 @@ static int __host_set_page_state_range(u64 addr, u64 size,
        return 0;
 }
 
-static int host_request_owned_transition(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_OWNED);
-}
-
-static int host_initiate_donation(u64 *completer_addr,
-                                 const struct pkvm_mem_transition *tx)
-{
-       u8 owner_id = tx->completer.id;
-       u64 size = tx->nr_pages * PAGE_SIZE;
-
-       *completer_addr = tx->initiator.host.completer_addr;
-       return host_stage2_set_owner_locked(tx->initiator.addr, size, owner_id);
-}
-
-static bool __host_ack_skip_pgtable_check(const struct pkvm_mem_transition *tx)
-{
-       return !(IS_ENABLED(CONFIG_NVHE_EL2_DEBUG) ||
-                tx->initiator.id != PKVM_ID_HYP);
-}
-
-static int __host_ack_transition(u64 addr, const struct pkvm_mem_transition *tx,
-                                enum pkvm_page_state state)
-{
-       u64 size = tx->nr_pages * PAGE_SIZE;
-
-       if (__host_ack_skip_pgtable_check(tx))
-               return 0;
-
-       return __host_check_page_state_range(addr, size, state);
-}
-
-static int host_ack_donation(u64 addr, const struct pkvm_mem_transition *tx)
-{
-       return __host_ack_transition(addr, tx, PKVM_NOPAGE);
-}
-
-static int host_complete_donation(u64 addr, const struct pkvm_mem_transition *tx)
-{
-       u64 size = tx->nr_pages * PAGE_SIZE;
-       u8 host_id = tx->completer.id;
-
-       return host_stage2_set_owner_locked(addr, size, host_id);
-}
-
 static enum pkvm_page_state hyp_get_page_state(kvm_pte_t pte, u64 addr)
 {
        if (!kvm_pte_valid(pte))
@@ -745,52 +662,6 @@ static int __hyp_check_page_state_range(u64 addr, u64 size,
        return check_page_state_range(&pkvm_pgtable, addr, size, &d);
 }
 
-static int hyp_request_donation(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.hyp.completer_addr;
-       return __hyp_check_page_state_range(addr, size, PKVM_PAGE_OWNED);
-}
-
-static int hyp_initiate_donation(u64 *completer_addr,
-                                const struct pkvm_mem_transition *tx)
-{
-       u64 size = tx->nr_pages * PAGE_SIZE;
-       int ret;
-
-       *completer_addr = tx->initiator.hyp.completer_addr;
-       ret = kvm_pgtable_hyp_unmap(&pkvm_pgtable, tx->initiator.addr, size);
-       return (ret != size) ? -EFAULT : 0;
-}
-
-static bool __hyp_ack_skip_pgtable_check(const struct pkvm_mem_transition *tx)
-{
-       return !(IS_ENABLED(CONFIG_NVHE_EL2_DEBUG) ||
-                tx->initiator.id != PKVM_ID_HOST);
-}
-
-static int hyp_ack_donation(u64 addr, const struct pkvm_mem_transition *tx)
-{
-       u64 size = tx->nr_pages * PAGE_SIZE;
-
-       if (__hyp_ack_skip_pgtable_check(tx))
-               return 0;
-
-       return __hyp_check_page_state_range(addr, size, PKVM_NOPAGE);
-}
-
-static int hyp_complete_donation(u64 addr,
-                                const struct pkvm_mem_transition *tx)
-{
-       void *start = (void *)addr, *end = start + (tx->nr_pages * PAGE_SIZE);
-       enum kvm_pgtable_prot prot = pkvm_mkstate(PAGE_HYP, PKVM_PAGE_OWNED);
-
-       return pkvm_create_mappings_locked(start, end, prot);
-}
-
 static enum pkvm_page_state guest_get_page_state(kvm_pte_t pte, u64 addr)
 {
        if (!kvm_pte_valid(pte))
@@ -812,94 +683,6 @@ 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_donation(struct pkvm_mem_donation *donation)
-{
-       const struct pkvm_mem_transition *tx = &donation->tx;
-       u64 completer_addr;
-       int ret;
-
-       switch (tx->initiator.id) {
-       case PKVM_ID_HOST:
-               ret = host_request_owned_transition(&completer_addr, tx);
-               break;
-       case PKVM_ID_HYP:
-               ret = hyp_request_donation(&completer_addr, tx);
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       if (ret)
-               return ret;
-
-       switch (tx->completer.id) {
-       case PKVM_ID_HOST:
-               ret = host_ack_donation(completer_addr, tx);
-               break;
-       case PKVM_ID_HYP:
-               ret = hyp_ack_donation(completer_addr, tx);
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       return ret;
-}
-
-static int __do_donate(struct pkvm_mem_donation *donation)
-{
-       const struct pkvm_mem_transition *tx = &donation->tx;
-       u64 completer_addr;
-       int ret;
-
-       switch (tx->initiator.id) {
-       case PKVM_ID_HOST:
-               ret = host_initiate_donation(&completer_addr, tx);
-               break;
-       case PKVM_ID_HYP:
-               ret = hyp_initiate_donation(&completer_addr, tx);
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       if (ret)
-               return ret;
-
-       switch (tx->completer.id) {
-       case PKVM_ID_HOST:
-               ret = host_complete_donation(completer_addr, tx);
-               break;
-       case PKVM_ID_HYP:
-               ret = hyp_complete_donation(completer_addr, tx);
-               break;
-       default:
-               ret = -EINVAL;
-       }
-
-       return ret;
-}
-
-/*
- * do_donate():
- *
- * The page owner transfers ownership to another component, losing access
- * as a consequence.
- *
- * Initiator: OWNED    => NOPAGE
- * Completer: NOPAGE   => OWNED
- */
-static int do_donate(struct pkvm_mem_donation *donation)
-{
-       int ret;
-
-       ret = check_donation(donation);
-       if (ret)
-               return ret;
-
-       return WARN_ON(__do_donate(donation));
-}
-
 int __pkvm_host_share_hyp(u64 pfn)
 {
        u64 phys = hyp_pfn_to_phys(pfn);
@@ -964,30 +747,29 @@ unlock:
 
 int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages)
 {
+       u64 phys = hyp_pfn_to_phys(pfn);
+       u64 size = PAGE_SIZE * nr_pages;
+       void *virt = __hyp_va(phys);
+       enum kvm_pgtable_prot prot;
        int ret;
-       u64 host_addr = hyp_pfn_to_phys(pfn);
-       u64 hyp_addr = (u64)__hyp_va(host_addr);
-       struct pkvm_mem_donation donation = {
-               .tx     = {
-                       .nr_pages       = nr_pages,
-                       .initiator      = {
-                               .id     = PKVM_ID_HOST,
-                               .addr   = host_addr,
-                               .host   = {
-                                       .completer_addr = hyp_addr,
-                               },
-                       },
-                       .completer      = {
-                               .id     = PKVM_ID_HYP,
-                       },
-               },
-       };
 
        host_lock_component();
        hyp_lock_component();
 
-       ret = do_donate(&donation);
+       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_OWNED);
+       WARN_ON(pkvm_create_mappings_locked(virt, virt + size, prot));
+       WARN_ON(host_stage2_set_owner_locked(phys, size, PKVM_ID_HYP));
+
+unlock:
        hyp_unlock_component();
        host_unlock_component();
 
@@ -996,30 +778,27 @@ int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages)
 
 int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages)
 {
+       u64 phys = hyp_pfn_to_phys(pfn);
+       u64 size = PAGE_SIZE * nr_pages;
+       u64 virt = (u64)__hyp_va(phys);
        int ret;
-       u64 host_addr = hyp_pfn_to_phys(pfn);
-       u64 hyp_addr = (u64)__hyp_va(host_addr);
-       struct pkvm_mem_donation donation = {
-               .tx     = {
-                       .nr_pages       = nr_pages,
-                       .initiator      = {
-                               .id     = PKVM_ID_HYP,
-                               .addr   = hyp_addr,
-                               .hyp    = {
-                                       .completer_addr = host_addr,
-                               },
-                       },
-                       .completer      = {
-                               .id     = PKVM_ID_HOST,
-                       },
-               },
-       };
 
        host_lock_component();
        hyp_lock_component();
 
-       ret = do_donate(&donation);
+       ret = __hyp_check_page_state_range(virt, size, PKVM_PAGE_OWNED);
+       if (ret)
+               goto unlock;
+       if (IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) {
+               ret = __host_check_page_state_range(phys, size, PKVM_NOPAGE);
+               if (ret)
+                       goto unlock;
+       }
 
+       WARN_ON(kvm_pgtable_hyp_unmap(&pkvm_pgtable, virt, size) != size);
+       WARN_ON(host_stage2_set_owner_locked(phys, size, PKVM_ID_HOST));
+
+unlock:
        hyp_unlock_component();
        host_unlock_component();