KVM: arm64: Expose unshare hypercall to the host
Introduce an unshare hypercall which can be used to unmap memory from
the hypervisor stage-1 in nVHE protected mode. This will be useful to
update the EL2 ownership state of pages during guest teardown, and
avoids keeping dangling mappings to unreferenced portions of memory.
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 0167f37..59c55ae 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -63,6 +63,7 @@
/* Hypercalls available after pKVM finalisation */
__KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp,
+ __KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_hyp,
__KVM_HOST_SMCCC_FUNC___kvm_adjust_pc,
__KVM_HOST_SMCCC_FUNC___kvm_vcpu_run,
__KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context,
diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index 5644558..80e9983 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -55,6 +55,7 @@
int __pkvm_prot_finalize(void);
int __pkvm_host_share_hyp(u64 pfn);
+int __pkvm_host_unshare_hyp(u64 pfn);
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/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index b096bf0..5e2197d 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -147,6 +147,13 @@
cpu_reg(host_ctxt, 1) = __pkvm_host_share_hyp(pfn);
}
+static void handle___pkvm_host_unshare_hyp(struct kvm_cpu_context *host_ctxt)
+{
+ DECLARE_REG(u64, pfn, host_ctxt, 1);
+
+ cpu_reg(host_ctxt, 1) = __pkvm_host_unshare_hyp(pfn);
+}
+
static void handle___pkvm_create_private_mapping(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(phys_addr_t, phys, host_ctxt, 1);
@@ -184,6 +191,7 @@
HANDLE_FUNC(__pkvm_prot_finalize),
HANDLE_FUNC(__pkvm_host_share_hyp),
+ HANDLE_FUNC(__pkvm_host_unshare_hyp),
HANDLE_FUNC(__kvm_adjust_pc),
HANDLE_FUNC(__kvm_vcpu_run),
HANDLE_FUNC(__kvm_flush_vm_context),
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 205616c..fc54258 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -757,3 +757,36 @@
return ret;
}
+
+int __pkvm_host_unshare_hyp(u64 pfn)
+{
+ 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,
+ },
+ },
+ .prot = PAGE_HYP,
+ };
+
+ host_lock_component();
+ hyp_lock_component();
+
+ ret = do_unshare(&share);
+
+ hyp_unlock_component();
+ host_unlock_component();
+
+ return ret;
+}
