[PATCH v6 07/18] KVM: arm64: Add PKVM_HYP_REQ_HYP_ALLOC request
Vincent Donnefort
vdonnefort at google.com
Thu Oct 1 07:28:38 PDT 2026
Introduce a new pkvm_hyp_request type asking the host to top up the pKVM
heap allocator.
Signed-off-by: Vincent Donnefort <vdonnefort at google.com>
Tested-by: Fuad Tabba <fuad.tabba at linux.dev>
Reviewed-by: Fuad Tabba <fuad.tabba at 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
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