In preparation for supporting protected guests, where guest memory
defaults to being inaccessible to the host, extend our memory protection
mechanisms to support donation of pages from the host to a specific
guest.
Signed-off-by: Will Deacon <w...@kernel.org>
---
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 1 +
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 62 +++++++++++++++++++
arch/arm64/kvm/hyp/pgtable.c | 2 +-
3 files changed, 64 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index 364432276fe0..b01b5cdb38de 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -69,6 +69,7 @@ int __pkvm_host_reclaim_page(u64 pfn);
int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages);
int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct kvm_vcpu *vcpu);
+int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct kvm_vcpu *vcpu);
bool addr_is_memory(phys_addr_t phys);
int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot
prot);
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 2e92be8bb463..d0544259eb01 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -890,6 +890,14 @@ static int guest_ack_share(u64 addr, const struct
pkvm_mem_transition *tx,
size, PKVM_NOPAGE);
}
+static int guest_ack_donation(u64 addr, const struct pkvm_mem_transition *tx)
+{
+ u64 size = tx->nr_pages * PAGE_SIZE;
+
+ return __guest_check_page_state_range(tx->completer.guest.vcpu, addr,
+ size, PKVM_NOPAGE);
+}
+
static int guest_complete_share(u64 addr, const struct pkvm_mem_transition *tx,
enum kvm_pgtable_prot perms)
{
@@ -903,6 +911,17 @@ static int guest_complete_share(u64 addr, const struct
pkvm_mem_transition *tx,
prot, &vcpu->arch.pkvm_memcache);
}
+static int guest_complete_donation(u64 addr, const struct pkvm_mem_transition
*tx)
+{
+ enum kvm_pgtable_prot prot = pkvm_mkstate(KVM_PGTABLE_PROT_RWX,
PKVM_PAGE_OWNED);
+ struct kvm_vcpu *vcpu = tx->completer.guest.vcpu;
+ struct kvm_shadow_vm *vm = get_shadow_vm(vcpu);
+ u64 size = tx->nr_pages * PAGE_SIZE;
+
+ return kvm_pgtable_stage2_map(&vm->pgt, addr, size,
tx->completer.guest.phys,
+ prot, &vcpu->arch.pkvm_memcache);
+}
+
static int check_share(struct pkvm_mem_share *share)
{
const struct pkvm_mem_transition *tx = &share->tx;
@@ -1088,6 +1107,9 @@ static int check_donation(struct pkvm_mem_donation
*donation)
case PKVM_ID_HYP:
ret = hyp_ack_donation(completer_addr, tx);
break;
+ case PKVM_ID_GUEST:
+ ret = guest_ack_donation(completer_addr, tx);
+ break;
default:
ret = -EINVAL;
}
@@ -1122,6 +1144,9 @@ static int __do_donate(struct pkvm_mem_donation *donation)
case PKVM_ID_HYP:
ret = hyp_complete_donation(completer_addr, tx);
break;
+ case PKVM_ID_GUEST:
+ ret = guest_complete_donation(completer_addr, tx);
+ break;
default:
ret = -EINVAL;
}
@@ -1362,6 +1387,43 @@ int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct
kvm_vcpu *vcpu)
return ret;
}
+int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct kvm_vcpu *vcpu)
+{
+ int ret;
+ u64 host_addr = hyp_pfn_to_phys(pfn);
+ u64 guest_addr = hyp_pfn_to_phys(gfn);
+ struct kvm_shadow_vm *vm = get_shadow_vm(vcpu);
+ struct pkvm_mem_donation donation = {
+ .tx = {
+ .nr_pages = 1,
+ .initiator = {
+ .id = PKVM_ID_HOST,
+ .addr = host_addr,
+ .host = {
+ .completer_addr = guest_addr,
+ },
+ },
+ .completer = {
+ .id = PKVM_ID_GUEST,
+ .guest = {
+ .vcpu = vcpu,
+ .phys = host_addr,
+ },
+ },
+ },
+ };
+
+ host_lock_component();
+ guest_lock_component(vm);
+
+ ret = do_donate(&donation);
+
+ guest_unlock_component(vm);
+ host_unlock_component();
+
+ return ret;
+}
+
static int hyp_zero_page(phys_addr_t phys)
{
void *addr;
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index a6676fd14cf9..2069e6833831 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -47,7 +47,7 @@
KVM_PTE_LEAF_ATTR_HI_S2_XN)
#define KVM_INVALID_PTE_OWNER_MASK GENMASK(9, 2)
-#define KVM_MAX_OWNER_ID 1
+#define KVM_MAX_OWNER_ID FIELD_MAX(KVM_INVALID_PTE_OWNER_MASK)
struct kvm_pgtable_walk_data {
struct kvm_pgtable *pgt;
--
2.36.1.124.g0e6072fb45-goog
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