[PATCH v2 5/6] arm64: hyperv: Route hypercalls through RSI host call in CCA Realms
From: Kameron Carr
Date: Thu Jun 25 2026 - 13:42:10 EST
Modify the five hypercall wrapper functions to check is_realm_world()
and use the per-CPU rsi_host_call structure when inside a Realm.
Signed-off-by: Kameron Carr <kameroncarr@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/hyperv/hv_core.c | 155 ++++++++++++++++++++++++++++--------
1 file changed, 121 insertions(+), 34 deletions(-)
diff --git a/arch/arm64/hyperv/hv_core.c b/arch/arm64/hyperv/hv_core.c
index e33a9e3c366a1..77cba08fca132 100644
--- a/arch/arm64/hyperv/hv_core.c
+++ b/arch/arm64/hyperv/hv_core.c
@@ -13,9 +13,41 @@
#include <linux/mm.h>
#include <linux/arm-smccc.h>
#include <linux/module.h>
+#include <linux/smp.h>
#include <asm-generic/bug.h>
#include <hyperv/hvhdk.h>
#include <asm/mshyperv.h>
+#include <asm/rsi.h>
+
+/*
+ * hv_do_rsi_hypercall - Helper function to invoke a hypercall from a
+ * Realm world using the RSI interface.
+ */
+static u64 hv_do_rsi_hypercall(u64 control, u64 input1, u64 input2)
+{
+ struct rsi_host_call *hostcall;
+ unsigned long flags;
+ u64 ret;
+
+ if (!hv_hostcall_array)
+ return HV_STATUS_INVALID_HYPERCALL_INPUT;
+
+ local_irq_save(flags);
+ hostcall = &hv_hostcall_array[smp_processor_id()];
+ memset(hostcall, 0, sizeof(*hostcall));
+ hostcall->gprs[0] = HV_FUNC_ID;
+ hostcall->gprs[1] = control;
+ hostcall->gprs[2] = input1;
+ hostcall->gprs[3] = input2;
+
+ if (rsi_host_call(virt_to_phys(hostcall)) == RSI_SUCCESS)
+ ret = hostcall->gprs[0];
+ else
+ ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+
+ local_irq_restore(flags);
+ return ret;
+}
/*
* hv_do_hypercall- Invoke the specified hypercall
@@ -29,8 +61,11 @@ u64 hv_do_hypercall(u64 control, void *input, void *output)
input_address = input ? virt_to_phys(input) : 0;
output_address = output ? virt_to_phys(output) : 0;
- arm_smccc_1_1_hvc(HV_FUNC_ID, control,
- input_address, output_address, &res);
+ if (is_realm_world())
+ return hv_do_rsi_hypercall(control, input_address, output_address);
+
+ arm_smccc_1_1_hvc(HV_FUNC_ID, control, input_address,
+ output_address, &res);
return res.a0;
}
EXPORT_SYMBOL_GPL(hv_do_hypercall);
@@ -48,6 +83,9 @@ u64 hv_do_fast_hypercall8(u16 code, u64 input)
control = (u64)code | HV_HYPERCALL_FAST_BIT;
+ if (is_realm_world())
+ return hv_do_rsi_hypercall(control, input, 0);
+
arm_smccc_1_1_hvc(HV_FUNC_ID, control, input, &res);
return res.a0;
}
@@ -65,6 +103,9 @@ u64 hv_do_fast_hypercall16(u16 code, u64 input1, u64 input2)
control = (u64)code | HV_HYPERCALL_FAST_BIT;
+ if (is_realm_world())
+ return hv_do_rsi_hypercall(control, input1, input2);
+
arm_smccc_1_1_hvc(HV_FUNC_ID, control, input1, input2, &res);
return res.a0;
}
@@ -76,24 +117,44 @@ EXPORT_SYMBOL_GPL(hv_do_fast_hypercall16);
void hv_set_vpreg(u32 msr, u64 value)
{
struct arm_smccc_res res;
+ struct rsi_host_call *hostcall;
+ unsigned long flags;
+ u64 status;
- arm_smccc_1_1_hvc(HV_FUNC_ID,
- HVCALL_SET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
- HV_HYPERCALL_REP_COMP_1,
- HV_PARTITION_ID_SELF,
- HV_VP_INDEX_SELF,
- msr,
- 0,
- value,
- 0,
- &res);
+ if (is_realm_world()) {
+ local_irq_save(flags);
+ hostcall = &hv_hostcall_array[smp_processor_id()];
+ memset(hostcall, 0, sizeof(*hostcall));
+ hostcall->gprs[0] = HV_FUNC_ID;
+ hostcall->gprs[1] = HVCALL_SET_VP_REGISTERS |
+ HV_HYPERCALL_FAST_BIT |
+ HV_HYPERCALL_REP_COMP_1;
+ hostcall->gprs[2] = HV_PARTITION_ID_SELF;
+ hostcall->gprs[3] = HV_VP_INDEX_SELF;
+ hostcall->gprs[4] = msr;
+ hostcall->gprs[6] = value;
+
+ if (rsi_host_call(virt_to_phys(hostcall)) == RSI_SUCCESS)
+ status = hostcall->gprs[0];
+ else
+ status = HV_STATUS_INVALID_HYPERCALL_INPUT;
+ local_irq_restore(flags);
+ } else {
+ arm_smccc_1_1_hvc(HV_FUNC_ID,
+ HVCALL_SET_VP_REGISTERS |
+ HV_HYPERCALL_FAST_BIT |
+ HV_HYPERCALL_REP_COMP_1,
+ HV_PARTITION_ID_SELF, HV_VP_INDEX_SELF, msr,
+ 0, value, 0, &res);
+ status = res.a0;
+ }
/*
- * Something is fundamentally broken in the hypervisor if
- * setting a VP register fails. There's really no way to
- * continue as a guest VM, so panic.
+ * Something is fundamentally broken in the hypervisor (or, in a
+ * Realm, the RMM denied the host call) if setting a VP register
+ * fails. There's really no way to continue as a guest VM, so panic.
*/
- BUG_ON(!hv_result_success(res.a0));
+ BUG_ON(!hv_result_success(status));
}
EXPORT_SYMBOL_GPL(hv_set_vpreg);
@@ -108,29 +169,55 @@ void hv_get_vpreg_128(u32 msr, struct hv_get_vp_registers_output *result)
{
struct arm_smccc_1_2_regs args;
struct arm_smccc_1_2_regs res;
+ struct rsi_host_call *hostcall;
+ unsigned long flags;
+ u64 status;
- args.a0 = HV_FUNC_ID;
- args.a1 = HVCALL_GET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
- HV_HYPERCALL_REP_COMP_1;
- args.a2 = HV_PARTITION_ID_SELF;
- args.a3 = HV_VP_INDEX_SELF;
- args.a4 = msr;
+ if (is_realm_world()) {
+ local_irq_save(flags);
+ hostcall = &hv_hostcall_array[smp_processor_id()];
+ memset(hostcall, 0, sizeof(*hostcall));
- /*
- * Use the SMCCC 1.2 interface because the results are in registers
- * beyond X0-X3.
- */
- arm_smccc_1_2_hvc(&args, &res);
+ hostcall->gprs[0] = HV_FUNC_ID;
+ hostcall->gprs[1] = HVCALL_GET_VP_REGISTERS |
+ HV_HYPERCALL_FAST_BIT |
+ HV_HYPERCALL_REP_COMP_1;
+ hostcall->gprs[2] = HV_PARTITION_ID_SELF;
+ hostcall->gprs[3] = HV_VP_INDEX_SELF;
+ hostcall->gprs[4] = msr;
+
+ if (rsi_host_call(virt_to_phys(hostcall)) == RSI_SUCCESS) {
+ status = hostcall->gprs[0];
+ result->as64.low = hostcall->gprs[6];
+ result->as64.high = hostcall->gprs[7];
+ } else {
+ status = HV_STATUS_INVALID_HYPERCALL_INPUT;
+ }
+ local_irq_restore(flags);
+ } else {
+ args.a0 = HV_FUNC_ID;
+ args.a1 = HVCALL_GET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
+ HV_HYPERCALL_REP_COMP_1;
+ args.a2 = HV_PARTITION_ID_SELF;
+ args.a3 = HV_VP_INDEX_SELF;
+ args.a4 = msr;
+
+ /*
+ * Use the SMCCC 1.2 interface because the results are in
+ * registers beyond X0-X3.
+ */
+ arm_smccc_1_2_hvc(&args, &res);
+ status = res.a0;
+ result->as64.low = res.a6;
+ result->as64.high = res.a7;
+ }
/*
- * Something is fundamentally broken in the hypervisor if
- * getting a VP register fails. There's really no way to
- * continue as a guest VM, so panic.
+ * Something is fundamentally broken in the hypervisor (or, in a
+ * Realm, the RMM denied the host call) if getting a VP register
+ * fails. There's really no way to continue as a guest VM, so panic.
*/
- BUG_ON(!hv_result_success(res.a0));
-
- result->as64.low = res.a6;
- result->as64.high = res.a7;
+ BUG_ON(!hv_result_success(status));
}
EXPORT_SYMBOL_GPL(hv_get_vpreg_128);
--
2.45.4