[PATCH v6 07/18] KVM: arm64: Add PKVM_HYP_REQ_HYP_ALLOC request

[Vincent Donnefort <vdonnefort@google.com>]

Introduce a new pkvm_hyp_request type asking the host to top up the pKVM
heap allocator.

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Tested-by: Fuad Tabba <fuad.tabba@linux.dev>
Reviewed-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 arch/arm64/include/asm/kvm_asm.h   |  1 +
 arch/arm64/include/asm/kvm_hcall.h |  6 ++++++
 arch/arm64/include/asm/kvm_pkvm.h  |  5 +++++
 arch/arm64/kvm/hyp/nvhe/hyp-main.c | 26 ++++++++++++++++++++++++++
 arch/arm64/kvm/pkvm.c              | 30 ++++++++++++++++++++++++++++++
 arch/arm64/kvm/trace_pkvm.h        |  6 ++++--
 6 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index e5b92ac09e69..de59e89318fa 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -89,6 +89,7 @@ enum __kvm_host_smccc_func {
 	__KVM_HOST_SMCCC_FUNC___vgic_v3_restore_vmcr_aprs,
 	__KVM_HOST_SMCCC_FUNC___vgic_v5_save_apr,
 	__KVM_HOST_SMCCC_FUNC___vgic_v5_restore_vmcr_apr,
+	__KVM_HOST_SMCCC_FUNC___pkvm_hyp_topup,
 
 	MARKER(__KVM_HOST_SMCCC_FUNC_PKVM_ONLY),
 
diff --git a/arch/arm64/include/asm/kvm_hcall.h b/arch/arm64/include/asm/kvm_hcall.h
index 9f06af58a4b0..6d6f12400e94 100644
--- a/arch/arm64/include/asm/kvm_hcall.h
+++ b/arch/arm64/include/asm/kvm_hcall.h
@@ -22,6 +22,10 @@
 
 typedef u16 pkvm_handle_t;
 
+enum pkvm_topup_id {
+	PKVM_TOPUP_HYP_ALLOC,
+};
+
 struct kvm;
 struct kvm_s2_mmu;
 struct kvm_vcpu;
@@ -193,6 +197,8 @@ DECLARE_KVM_HOST_HCALL(void, __vgic_v5_save_apr,
 	struct vgic_v5_cpu_if __kern *, cpu_if)
 DECLARE_KVM_HOST_HCALL(void, __vgic_v5_restore_vmcr_apr,
 	struct vgic_v5_cpu_if __kern *, cpu_if)
+DECLARE_KVM_HOST_HCALL(int, __pkvm_hyp_topup,
+	enum pkvm_topup_id, id, phys_addr_t, head, unsigned long, nr_pages)
 
 /* Hypercalls that are available only when pKVM has finalised. */
 DECLARE_KVM_HOST_HCALL(int, __pkvm_host_share_hyp,
diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h
index 19bddf261c82..c338178d6bb2 100644
--- a/arch/arm64/include/asm/kvm_pkvm.h
+++ b/arch/arm64/include/asm/kvm_pkvm.h
@@ -207,6 +207,7 @@ struct pkvm_mapping {
 
 enum pkvm_hyp_req_type {
 	PKVM_HYP_NO_REQ = 0,
+	PKVM_HYP_REQ_HYP_ALLOC,
 	__PKVM_HYP_REQ_TYPE_MAX,
 };
 
@@ -228,9 +229,13 @@ struct pkvm_hyp_req {
 
 static inline size_t pkvm_hyp_req_arg_size(u8 type)
 {
+	struct pkvm_hyp_req *req;
+
 	switch (type) {
 	case PKVM_HYP_NO_REQ:
 		return 0;
+	case PKVM_HYP_REQ_HYP_ALLOC:
+		return sizeof(req->mem);
 	default:
 		WARN_ON(1);
 	}
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 91e74a1a334f..2b89eb274482 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -17,6 +17,7 @@
 #include <asm/kvm_hypevents.h>
 #include <asm/kvm_mmu.h>
 
+#include <nvhe/alloc.h>
 #include <nvhe/ffa.h>
 #include <nvhe/mem_protect.h>
 #include <nvhe/mm.h>
@@ -799,6 +800,30 @@ DEFINE_KVM_HOST_HCALL(int, __pkvm_finalize_teardown_vm,
 	return __pkvm_finalize_teardown_vm(handle);
 }
 
+DEFINE_KVM_HOST_HCALL(int, __pkvm_hyp_topup,
+	enum pkvm_topup_id, id, phys_addr_t, head, unsigned long, nr_pages)
+{
+	struct kvm_cpu_context *host_ctxt = host_data_ptr(host_ctxt);
+	struct kvm_hyp_memcache host_mc = {
+		.head = head,
+		.nr_pages = nr_pages,
+	};
+	int ret;
+
+	switch (id) {
+	case PKVM_TOPUP_HYP_ALLOC:
+		ret = hyp_alloc_topup(&host_mc);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	cpu_reg(host_ctxt, 2) = host_mc.head;
+	cpu_reg(host_ctxt, 3) = host_mc.nr_pages;
+
+	return ret;
+}
+
 DEFINE_KVM_HOST_HCALL(int, __tracing_load,
 	void __kern *, desc_hva, size_t, desc_size)
 {
@@ -893,6 +918,7 @@ static const hcall_t host_hcall[] = {
 	HANDLE_FUNC(__vgic_v3_restore_vmcr_aprs),
 	HANDLE_FUNC(__vgic_v5_save_apr),
 	HANDLE_FUNC(__vgic_v5_restore_vmcr_apr),
+	HANDLE_FUNC(__pkvm_hyp_topup),
 
 	HANDLE_FUNC(__pkvm_host_share_hyp),
 	HANDLE_FUNC(__pkvm_host_unshare_hyp),
diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
index 11d9e2f70cd8..9cd23978481c 100644
--- a/arch/arm64/kvm/pkvm.c
+++ b/arch/arm64/kvm/pkvm.c
@@ -88,6 +88,33 @@ void __init kvm_hyp_reserve(void)
 		 hyp_mem_base);
 }
 
+static int pkvm_hyp_topup(enum pkvm_topup_id id, unsigned long nr_pages)
+{
+	struct kvm_hyp_memcache mc;
+	struct arm_smccc_res res;
+	int ret;
+
+	init_hyp_memcache(&mc);
+	ret = topup_hyp_memcache(&mc, nr_pages);
+	if (ret)
+		goto err;
+
+	arm_smccc_1_1_hvc(KVM_HOST_SMCCC_FUNC(__pkvm_hyp_topup), id, mc.head,
+			  mc.nr_pages, &res);
+	if (WARN_ON_ONCE(res.a0 != SMCCC_RET_SUCCESS)) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	ret = res.a1;
+	mc.head = res.a2;
+	mc.nr_pages = res.a3;
+
+err:
+	free_hyp_memcache(&mc);
+	return ret;
+}
+
 static void __pkvm_destroy_hyp_vm(struct kvm *kvm)
 {
 	if (pkvm_hyp_vm_is_created(kvm)) {
@@ -603,6 +630,9 @@ static int pkvm_handle_hyp_req(struct pkvm_hyp_req *req)
 	int ret = -EINVAL;
 
 	switch (req->type) {
+	case PKVM_HYP_REQ_HYP_ALLOC:
+		ret = pkvm_hyp_topup(PKVM_TOPUP_HYP_ALLOC, req->mem.nr_pages);
+		break;
 	}
 
 	trace_kvm_handle_pkvm_hyp_req(req, ret);
diff --git a/arch/arm64/kvm/trace_pkvm.h b/arch/arm64/kvm/trace_pkvm.h
index 3966c111e3ad..493225e3282d 100644
--- a/arch/arm64/kvm/trace_pkvm.h
+++ b/arch/arm64/kvm/trace_pkvm.h
@@ -9,9 +9,11 @@
 #define TRACE_SYSTEM kvm
 
 TRACE_DEFINE_ENUM(PKVM_HYP_NO_REQ);
+TRACE_DEFINE_ENUM(PKVM_HYP_REQ_HYP_ALLOC);
 
-#define PKVM_HYP_REQ_TYPES \
-	{ PKVM_HYP_NO_REQ, "NO_REQ" }
+#define PKVM_HYP_REQ_TYPES				\
+	{ PKVM_HYP_NO_REQ, "NO_REQ" },			\
+	{ PKVM_HYP_REQ_HYP_ALLOC, "HYP_ALLOC" }
 
 TRACE_EVENT(kvm_handle_pkvm_hyp_req,
 	TP_PROTO(struct pkvm_hyp_req *req, int ret),
-- 
2.56.0.rc1.315.gc6ed9934b7-goog