[PATCH v4 3/6] arm64: hyperv: Add per-CPU RSI host call infrastructure for CCA Realms
WARM1d
REVIEWED: 1 (0M)
From: Kameron Carr <hidden>
Date: 2026-10-01 22:07:01
Also in:
linux-arch, linux-arm-kernel, lkml
Subsystem:
arm64 port (aarch64 architecture), hyper-v/azure core and drivers, the rest · Maintainers:
Catalin Marinas, Will Deacon, "K. Y. Srinivasan", Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Linus Torvalds
Revision v4 of 5 in this series; 1 review trailer.
Revisions (5)
Arm CCA Realms cannot issue Hyper-V hypercalls via HVC; the guest must route them through the RSI_HOST_CALL interface, which takes the IPA of a per-CPU rsi_host_call structure as its argument. Add hv_hostcall_array as a per-CPU struct array and allocate it during hyperv_init(). The allocation is gated on is_realm_world() so non-Realm arm64 Hyper-V guests pay no memory cost. Reviewed-by: Michael Kelley <redacted> Signed-off-by: Kameron Carr <redacted> --- arch/arm64/hyperv/mshyperv.c | 28 ++++++++++++++++++++++++++-- arch/arm64/include/asm/mshyperv.h | 4 ++++ 2 files changed, 30 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index 4fdc26a..b1657cf 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c@@ -11,14 +11,19 @@ #include <linux/types.h> #include <linux/acpi.h> +#include <linux/arm-rsi-cmds.h> #include <linux/export.h> #include <linux/errno.h> +#include <linux/slab.h> #include <linux/version.h> #include <linux/cpuhotplug.h> #include <asm/mshyperv.h> static bool hyperv_initialized; +struct rsi_host_call *hv_hostcall_array; +EXPORT_SYMBOL_GPL(hv_hostcall_array); + int hv_get_hypervisor_version(union hv_hypervisor_version_info *info) { hv_get_vpreg_128(HV_REGISTER_HYPERVISOR_VERSION,
@@ -85,6 +90,20 @@ static int __init hyperv_init(void) if (!hyperv_detect_via_acpi() && !hyperv_detect_via_smccc()) return 0; + /* + * The RSI host-call buffers are only ever used when + * is_realm_world() is true. Skip the allocation on non-Realm + * guests. A single contiguous array of nr_cpu_ids entries is + * allocated; each CPU indexes into it by its processor ID. + */ + if (is_realm_world()) { + hv_hostcall_array = kcalloc(nr_cpu_ids, + sizeof(struct rsi_host_call), + GFP_KERNEL); + if (!hv_hostcall_array) + return -ENOMEM; + } + /* Setup the guest ID */ guest_id = hv_generate_guest_id(LINUX_VERSION_CODE); hv_set_vpreg(HV_REGISTER_GUEST_OS_ID, guest_id);
@@ -106,13 +125,13 @@ static int __init hyperv_init(void) ret = hv_common_init(); if (ret) - return ret; + goto free_hostcall_mem; ret = cpuhp_setup_state(CPUHP_AP_HYPERV_ONLINE, "arm64/hyperv_init:online", hv_common_cpu_init, hv_common_cpu_die); if (ret < 0) { hv_common_free(); - return ret; + goto free_hostcall_mem; } if (ms_hyperv.priv_high & HV_ACCESS_PARTITION_ID)
@@ -125,6 +144,11 @@ static int __init hyperv_init(void) hyperv_initialized = true; return 0; + +free_hostcall_mem: + kfree(hv_hostcall_array); + hv_hostcall_array = NULL; + return ret; } early_initcall(hyperv_init);
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index b721d31..aed0aa5 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h@@ -61,6 +61,10 @@ static inline u64 hv_get_non_nested_msr(unsigned int reg) ARM_SMCCC_OWNER_VENDOR_HYP, \ HV_SMCCC_FUNC_NUMBER) +/* Per-CPU-indexed RSI host call structures for CCA Realms */ +struct rsi_host_call; +extern struct rsi_host_call *hv_hostcall_array; + #include <asm-generic/mshyperv.h> #endif
--
2.45.4