[PATCH v2 11/20] KVM: s390: arm64: Query Available Arm features
From: Steffen Eiden
Date: Mon Aug 31 2026 - 14:58:56 EST
QAAF enables s390 hosts to gain information about the support
and handling of various arm features supported by the machine.
Function code 1 provides general information about available formats,
machine defined content of system/id register, and other various
information for running arm guests.
Function code 2 provides a initialised save area.
Co-developed-by: Andreas Grapentin <gra@xxxxxxxxxxxxx>
Signed-off-by: Andreas Grapentin <gra@xxxxxxxxxxxxx>
Signed-off-by: Steffen Eiden <seiden@xxxxxxxxxxxxx>
---
arch/s390/include/asm/aef.h | 28 +++++
arch/s390/include/asm/kvm_host_arm64_types.h | 111 +++++++++++++++++++
arch/s390/include/asm/sae.h | 25 +++++
arch/s390/kernel/Makefile | 2 +-
arch/s390/kernel/aef.c | 101 +++++++++++++++++
arch/s390/kvm/arm64/Makefile | 1 +
arch/s390/kvm/arm64/arm.c | 3 +-
arch/s390/kvm/arm64/qaaf.c | 69 ++++++++++++
arch/s390/kvm/arm64/qaaf.h | 10 ++
arch/s390/tools/opcodes.txt | 1 +
10 files changed, 349 insertions(+), 2 deletions(-)
create mode 100644 arch/s390/include/asm/aef.h
create mode 100644 arch/s390/kernel/aef.c
create mode 100644 arch/s390/kvm/arm64/qaaf.c
create mode 100644 arch/s390/kvm/arm64/qaaf.h
diff --git a/arch/s390/include/asm/aef.h b/arch/s390/include/asm/aef.h
new file mode 100644
index 000000000000..2f29e3875d4e
--- /dev/null
+++ b/arch/s390/include/asm/aef.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _ASM_S390_AEF_H
+#define _ASM_S390_AEF_H
+
+#include <asm/kvm_host_arm64_types.h>
+
+/**
+ * kvm_init_save_area() - Initialize Guest Save Area
+ * @save_area: Pointer to kvm_sae_save_area structure to initialize
+ *
+ * Context: Must be called before using the save area with lasrm/stiasrm instructions.
+ */
+void kvm_vcpu_init_save_area(struct kvm_sae_save_area *sa);
+struct qaaf_qmc_block *aef_qmc(void);
+
+struct aef_info {
+ unsigned long arm_guest_supp;
+ unsigned long sae_avail;
+ unsigned long ptff_avail;
+ unsigned long supp_state_desc_formats;
+ unsigned long supp_save_area_formats;
+ unsigned long max_num_vcpu;
+};
+
+const struct aef_info *aef_info(void);
+
+#endif /* _ASM_S390_AEF_H */
diff --git a/arch/s390/include/asm/kvm_host_arm64_types.h b/arch/s390/include/asm/kvm_host_arm64_types.h
index 2c922ef478d1..93fd649a26f4 100644
--- a/arch/s390/include/asm/kvm_host_arm64_types.h
+++ b/arch/s390/include/asm/kvm_host_arm64_types.h
@@ -115,4 +115,115 @@ struct kvm_sae_save_area {
} __packed __aligned(PAGE_SIZE);
static_assert(sizeof(struct kvm_sae_save_area) == PAGE_SIZE);
+#define QAAF_FC_QMC 1
+#define QAAF_FC_GISRSA 2
+
+union qaaf_gr0_gisrsa {
+ struct {
+ u8 _0000[6];
+ u8 saf;
+ u8 : 2;
+ u8 fc : 6;
+ };
+ u64 val;
+};
+
+static_assert(sizeof(union qaaf_gr0_gisrsa) == sizeof(u64));
+
+/* QAAF Query Model Capabilities */
+struct qaaf_qmc_block {
+ u64 _0000; /* 0x0000 */
+ u8 ssdf; /* 0x0008 */
+ u8 _0009; /* 0x0009 */
+ u8 ssaf; /* 0x000a */
+ u8 _000b[3]; /* 0x000b */
+ u16 maxncpu; /* 0x000e */
+ u64 regs[0x1fe]; /* 0x0010 */
+} __aligned(PAGE_SIZE);
+static_assert(sizeof(struct qaaf_qmc_block) == PAGE_SIZE);
+
+union qaaf_block {
+ struct qaaf_qmc_block qmc;
+ struct kvm_sae_save_area save_area;
+} __aligned(PAGE_SIZE);
+static_assert(sizeof(union qaaf_block) == PAGE_SIZE);
+
+/*
+ * Keep in sync with mapping from SYS_* to QAAF_* in feature.c!
+ */
+enum {
+ QAAF_REG_MIDR_EL1 = 0x02,
+ /* 0x03 -0x06 reserved */
+ QAAF_REG_MPIDR_EL1 = 0x07,
+ QAAF_REG_REVIDR_EL1 = 0x08,
+ /* 0x09 reserved */
+ QAAF_REG_ID_PFR0_EL1 = 0x0a,
+ QAAF_REG_ID_PFR1_EL1 = 0x0b,
+ QAAF_REG_ID_DFR0_EL1 = 0x0c,
+ QAAF_REG_ID_AFR0_EL1 = 0x0d,
+ QAAF_REG_ID_MMFR0_EL1 = 0x0e,
+ QAAF_REG_ID_MMFR1_EL1 = 0x0f,
+ QAAF_REG_ID_MMFR2_EL1 = 0x10,
+ QAAF_REG_ID_MMFR3_EL1 = 0x11,
+ QAAF_REG_ID_ISAR0_EL1 = 0x12,
+ QAAF_REG_ID_ISAR1_EL1 = 0x13,
+ QAAF_REG_ID_ISAR2_EL1 = 0x14,
+ QAAF_REG_ID_ISAR3_EL1 = 0x15,
+ QAAF_REG_ID_ISAR4_EL1 = 0x16,
+ QAAF_REG_ID_ISAR5_EL1 = 0x17,
+ QAAF_REG_ID_MMFR4_EL1 = 0x18,
+ QAAF_REG_ID_ISAR6_EL1 = 0x19,
+ QAAF_REG_MVFR0_EL1 = 0x1a,
+ QAAF_REG_MVFR1_EL1 = 0x1b,
+ QAAF_REG_MVFR2_EL1 = 0x1c,
+ /* 0x1d reserved */
+ QAAF_REG_ID_PFR2_EL1 = 0x1e,
+ QAAF_REG_ID_DFR1_EL1 = 0x1f,
+ QAAF_REG_ID_MMFR5_EL1 = 0x20,
+ /* 0x21 reserved */
+ QAAF_REG_ID_AA64PFR0_EL1 = 0x22,
+ QAAF_REG_ID_AA64PFR1_EL1 = 0x23,
+ QAAF_REG_ID_AA64PFR2_EL1 = 0x24,
+ /* 0x25 reserved */
+ QAAF_REG_ID_AA64ZFR0_EL1 = 0x26,
+ QAAF_REG_ID_AA64SMFR0_EL1 = 0x27,
+ /* 0x28 reserved */
+ QAAF_REG_ID_AA64FPFR0_EL1 = 0x29,
+ QAAF_REG_ID_AA64DFR0_EL1 = 0x2a,
+ QAAF_REG_ID_AA64DFR1_EL1 = 0x2b,
+ QAAF_REG_ID_AA64DFR2_EL1 = 0x2c,
+ /* 0x2d reserved */
+ QAAF_REG_ID_AA64AFR0_EL1 = 0x2e,
+ QAAF_REG_ID_AA64AFR1_EL1 = 0x2f,
+ /* 0x30,0x31 reserved */
+ QAAF_REG_ID_AA64ISAR0_EL1 = 0x32,
+ QAAF_REG_ID_AA64ISAR1_EL1 = 0x33,
+ QAAF_REG_ID_AA64ISAR2_EL1 = 0x34,
+ QAAF_REG_ID_AA64ISAR3_EL1 = 0x35,
+ /* 0x36-0x39 reserved */
+ QAAF_REG_ID_AA64MMFR0_EL1 = 0x3a,
+ QAAF_REG_ID_AA64MMFR1_EL1 = 0x3b,
+ QAAF_REG_ID_AA64MMFR2_EL1 = 0x3c,
+ QAAF_REG_ID_AA64MMFR3_EL1 = 0x3d,
+ QAAF_REG_ID_AA64MMFR4_EL1 = 0x3e,
+ /* 0x3f-0x41 reserved */
+ QAAF_REG_CNTFRQ_EL0 = 0x42,
+ QAAF_REG_CTR_EL0 = 0x43,
+ QAAF_REG_AIDR_EL1 = 0x44,
+ /* 0x43-0x49 reserved */
+ QAAF_IRPTC = 0x4a,
+ /* 0x4b reserved */
+ QAAF_REG_ICH_VTR_EL2 = 0x4c,
+ QAAF_GIC_ATTR = 0x4d,
+ /* 0x4E-0x51 reserved */
+ QAAF_REG_PMMIR_EL1 = 0x52,
+ QAAF_REG_PMCR_EL0 = 0x53,
+ QAAF_REG_PMCEID0_EL0 = 0x54,
+ QAAF_REG_PMCEID1_EL0 = 0x55,
+ /* 0x56-0x1ff reserved */
+ _QAAF_MAX
+};
+
+static_assert(sizeof(struct qaaf_qmc_block) / 8 + 1 >= _QAAF_MAX);
+
#endif /* ASM_KVM_HOST_ARM64_TYPES_H */
diff --git a/arch/s390/include/asm/sae.h b/arch/s390/include/asm/sae.h
index 6580536544ee..f88d15b8f1e9 100644
--- a/arch/s390/include/asm/sae.h
+++ b/arch/s390/include/asm/sae.h
@@ -111,5 +111,30 @@ static __always_inline void lasrm(struct kvm_sae_save_area *save_area)
);
}
+/**
+ * qaaf() - Query Available Arm Features
+ * @gr0: QAAF function code, placed in greg 0
+ * @qaaf_block: Pointer to the page for the output
+ *
+ * Perform QAAF. The result ins written to qaaf_block.
+ */
+static __always_inline int qaaf(u64 gr0, union qaaf_block *qaaf_block)
+{
+ int exception = 1;
+
+ asm volatile(
+ " lgr 0,%[r0]\n"
+ " .insn rre,0xb9ad0000,%[r1],0\n"
+ "0: lhi %[exc],0\n"
+ "1:\n"
+ EX_TABLE(0b, 1b)
+ : "=m"(*qaaf_block), [exc] "+d"(exception)
+ : [r1] "a"(qaaf_block), [r0] "d"(gr0)
+ : "r0"
+ );
+
+ return exception;
+}
+
#endif /* !__ASSEMBLER__ */
#endif /* __ASM_S390_SAE_H */
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index f84b8fb41331..0f3b9fcd1885 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -46,7 +46,7 @@ obj-y += runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o
obj-y += entry.o reipl.o kdebugfs.o alternative.o skey.o
obj-y += nospec-branch.o ipl_vmparm.o machine_kexec_reloc.o unwind_bc.o
obj-y += smp.o text_amode31.o stacktrace.o abs_lowcore.o facility.o uv.o wti.o
-obj-y += diag/
+obj-y += diag/ aef.o
always-$(KBUILD_BUILTIN) += vmlinux.lds
diff --git a/arch/s390/kernel/aef.c b/arch/s390/kernel/aef.c
new file mode 100644
index 000000000000..825e2643a892
--- /dev/null
+++ b/arch/s390/kernel/aef.c
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "linux/export.h"
+#include <linux/kconfig.h>
+#include <linux/sysfs.h>
+#include <linux/kobject.h>
+#include <linux/slab.h>
+
+#include <asm/aef.h>
+#include <asm/boot_data.h>
+#include <asm/sae.h>
+#include <asm/sclp.h>
+#include <asm/sections.h>
+
+static struct qaaf_qmc_block qmc = {};
+static struct kvm_sae_save_area save_area = {};
+static struct aef_info info = {};
+
+/**
+ * kvm_init_save_area() - Initialize Guest Save Area
+ * @save_area: Pointer to kvm_sae_save_area structure to initialize
+ *
+ * Context: Must be called before using the save area with lasrm/stiasrm instructions.
+ */
+void kvm_vcpu_init_save_area(struct kvm_sae_save_area *sa)
+{
+ memcpy(sa, &save_area, sizeof(save_area));
+}
+EXPORT_SYMBOL(kvm_vcpu_init_save_area);
+
+struct qaaf_qmc_block *aef_qmc(void)
+{
+ return &qmc;
+}
+EXPORT_SYMBOL(aef_qmc);
+
+const struct aef_info *aef_info(void)
+{
+ return &info;
+}
+EXPORT_SYMBOL(aef_info);
+
+static int __init aef_init_save_area(void)
+{
+ int ret;
+
+ union qaaf_gr0_gisrsa gr0 = {
+ .fc = QAAF_FC_GISRSA,
+ .saf = SAE_SAVE_AREA_FORMAT_0,
+ };
+
+ ret = qaaf(gr0.val, (union qaaf_block *)&save_area);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static int __init aef_query_info(void)
+{
+ int ret;
+
+ if (IS_ENABLED(CONFIG_KVM_S390_ARM64)) {
+ info.sae_avail = sclp.has_aef;
+ info.ptff_avail = ptff_query(PTFF_QAGTO) &&
+ ptff_query(PTFF_QAGPT);
+ info.arm_guest_supp = info.sae_avail && info.ptff_avail;
+ }
+ if (!info.sae_avail)
+ return 0;
+
+ ret = qaaf(QAAF_FC_QMC, (union qaaf_block *)&qmc);
+ if (ret)
+ return ret;
+
+ info.supp_state_desc_formats = qmc.ssdf;
+ info.supp_save_area_formats = qmc.ssaf;
+ info.max_num_vcpu = qmc.maxncpu;
+
+ return 0;
+}
+
+static int __init aef_sysfs_init(void)
+{
+ int rc = -ENOMEM;
+
+ if (!IS_ENABLED(CONFIG_KVM_S390_ARM64))
+ return 0;
+
+ rc = aef_query_info();
+ if (rc)
+ return rc;
+
+ rc = aef_init_save_area();
+ if (rc)
+ return rc;
+
+ return 0;
+}
+
+arch_initcall(aef_sysfs_init);
diff --git a/arch/s390/kvm/arm64/Makefile b/arch/s390/kvm/arm64/Makefile
index ae614a62f7b5..577b0653a68e 100644
--- a/arch/s390/kvm/arm64/Makefile
+++ b/arch/s390/kvm/arm64/Makefile
@@ -14,6 +14,7 @@ kvm-arm64-obj := \
inject_fault.o \
mmio.o \
mmu.o \
+ qaaf.o \
reset.o \
kvm-arm64-obj += $(patsubst %.o,%-arm64.o,$(kvm-y))
diff --git a/arch/s390/kvm/arm64/arm.c b/arch/s390/kvm/arm64/arm.c
index 2740ee3b703e..664fea5cf6b5 100644
--- a/arch/s390/kvm/arm64/arm.c
+++ b/arch/s390/kvm/arm64/arm.c
@@ -12,6 +12,7 @@
#include <linux/bitfield.h>
#include <asm/access-regs.h>
+#include <asm/aef.h>
#include <arm64/kvm_emulate.h>
#include <arm64/sysreg.h>
@@ -744,7 +745,7 @@ long kvm_arch_vcpu_unlocked_ioctl(struct file *filp, unsigned int ioctl,
static int __init kvm_s390_arm64_init(void)
{
- if (!sclp.has_aef)
+ if (!aef_info()->arm_guest_supp)
return -ENXIO;
return kvm_init_with_dev(sizeof(struct kvm_vcpu), 0, THIS_MODULE,
diff --git a/arch/s390/kvm/arm64/qaaf.c b/arch/s390/kvm/arm64/qaaf.c
new file mode 100644
index 000000000000..c3124d38afc2
--- /dev/null
+++ b/arch/s390/kvm/arm64/qaaf.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/kvm_host.h>
+#include <asm/aef.h>
+#include "qaaf.h"
+
+#define _qaaf_reg_case(id) case SYS_##id: return aef_qmc()->regs[QAAF_REG_##id]
+
+u64 kvm_qaaf_read_ftr_reg(u32 id)
+{
+ switch (id) {
+ _qaaf_reg_case(MIDR_EL1);
+ _qaaf_reg_case(MPIDR_EL1);
+ _qaaf_reg_case(REVIDR_EL1);
+ _qaaf_reg_case(ID_PFR0_EL1);
+ _qaaf_reg_case(ID_PFR1_EL1);
+ _qaaf_reg_case(ID_DFR0_EL1);
+ _qaaf_reg_case(ID_AFR0_EL1);
+ _qaaf_reg_case(ID_MMFR0_EL1);
+ _qaaf_reg_case(ID_MMFR1_EL1);
+ _qaaf_reg_case(ID_MMFR2_EL1);
+ _qaaf_reg_case(ID_MMFR3_EL1);
+ _qaaf_reg_case(ID_ISAR0_EL1);
+ _qaaf_reg_case(ID_ISAR1_EL1);
+ _qaaf_reg_case(ID_ISAR2_EL1);
+ _qaaf_reg_case(ID_ISAR3_EL1);
+ _qaaf_reg_case(ID_ISAR4_EL1);
+ _qaaf_reg_case(ID_ISAR5_EL1);
+ _qaaf_reg_case(ID_MMFR4_EL1);
+ _qaaf_reg_case(ID_ISAR6_EL1);
+ _qaaf_reg_case(MVFR0_EL1);
+ _qaaf_reg_case(MVFR1_EL1);
+ _qaaf_reg_case(MVFR2_EL1);
+ _qaaf_reg_case(ID_PFR2_EL1);
+ _qaaf_reg_case(ID_DFR1_EL1);
+ _qaaf_reg_case(ID_MMFR5_EL1);
+ _qaaf_reg_case(ID_AA64PFR0_EL1);
+ _qaaf_reg_case(ID_AA64PFR1_EL1);
+ _qaaf_reg_case(ID_AA64PFR2_EL1);
+ _qaaf_reg_case(ID_AA64ZFR0_EL1);
+ _qaaf_reg_case(ID_AA64SMFR0_EL1);
+ _qaaf_reg_case(ID_AA64FPFR0_EL1);
+ _qaaf_reg_case(ID_AA64DFR0_EL1);
+ _qaaf_reg_case(ID_AA64DFR1_EL1);
+ _qaaf_reg_case(ID_AA64DFR2_EL1);
+ _qaaf_reg_case(ID_AA64AFR0_EL1);
+ _qaaf_reg_case(ID_AA64AFR1_EL1);
+ _qaaf_reg_case(ID_AA64ISAR0_EL1);
+ _qaaf_reg_case(ID_AA64ISAR1_EL1);
+ _qaaf_reg_case(ID_AA64ISAR2_EL1);
+ _qaaf_reg_case(ID_AA64ISAR3_EL1);
+ _qaaf_reg_case(ID_AA64MMFR0_EL1);
+ _qaaf_reg_case(ID_AA64MMFR1_EL1);
+ _qaaf_reg_case(ID_AA64MMFR2_EL1);
+ _qaaf_reg_case(ID_AA64MMFR3_EL1);
+ _qaaf_reg_case(ID_AA64MMFR4_EL1);
+ _qaaf_reg_case(CNTFRQ_EL0);
+ _qaaf_reg_case(CTR_EL0);
+ _qaaf_reg_case(AIDR_EL1);
+ _qaaf_reg_case(ICH_VTR_EL2);
+ _qaaf_reg_case(PMMIR_EL1);
+ _qaaf_reg_case(PMCR_EL0);
+ _qaaf_reg_case(PMCEID0_EL0);
+ _qaaf_reg_case(PMCEID1_EL0);
+ default:
+ WARN(true, "Unknown feature register 0x%x\n", id);
+ return 0xbad1234bad;
+ }
+}
diff --git a/arch/s390/kvm/arm64/qaaf.h b/arch/s390/kvm/arm64/qaaf.h
new file mode 100644
index 000000000000..8fed7f795ce0
--- /dev/null
+++ b/arch/s390/kvm/arm64/qaaf.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef ARCH_S390_KVM_ARM64_QAAF_H
+#define ARCH_S390_KVM_ARM64_QAAF_H
+
+#include <asm/aef.h>
+
+u64 kvm_qaaf_read_ftr_reg(u32 id);
+
+#endif
diff --git a/arch/s390/tools/opcodes.txt b/arch/s390/tools/opcodes.txt
index 18af14071290..fd5483107961 100644
--- a/arch/s390/tools/opcodes.txt
+++ b/arch/s390/tools/opcodes.txt
@@ -600,6 +600,7 @@ b9a7 stiasrm RRE_R0
b9aa lptea RRF_RURR2
b9ab essa RRF_U0RR
b9ac irbm RRE_RR
+b9ad qaaf RRE_R0
b9ae rrbm RRE_RR
b9af pfmf RRE_RR
b9b0 cu14 RRF_U0RR
--
2.53.0