[PATCH v3 1/8] arm64: KVM: Use static keys for selecting the GIC backend
Vladimir Murzin
vladimir.murzin at arm.com
Thu Sep 8 09:06:43 PDT 2016
Currently GIC backend is selected via alternative framework and this
is fine. We are going to introduce vgic-v3 to 32-bit world and there
we don't have patching framework in hand, so we can either check
support for GICv3 every time we need to choose which backend to use or
try to optimise it by using static keys. The later looks quite
promising because we can share logic involved in selecting GIC backend
between architectures if both uses static keys.
This patch moves arm64 from alternative to static keys framework for
selecting GIC backend. To make static keys work on hyp side we need to
make sure that hyp can access to the key which is RW data. For that
purpose introduce __hyp_data section we can map to hyp and place the
key there.
Signed-off-by: Vladimir Murzin <vladimir.murzin at arm.com>
---
arch/arm/include/asm/kvm_host.h | 13 +++++++++++++
arch/arm/include/asm/kvm_hyp.h | 2 --
arch/arm/include/asm/virt.h | 8 ++++++++
arch/arm/kernel/vmlinux.lds.S | 6 ++++++
arch/arm/kvm/arm.c | 19 +++++++++++++++++++
arch/arm64/include/asm/kvm_host.h | 15 +++++++++++++++
arch/arm64/include/asm/kvm_hyp.h | 2 --
arch/arm64/include/asm/virt.h | 7 +++++++
arch/arm64/kernel/vmlinux.lds.S | 6 ++++++
arch/arm64/kvm/hyp/switch.c | 19 +++++++++----------
10 files changed, 83 insertions(+), 14 deletions(-)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index de338d9..bfa6eec 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -21,11 +21,14 @@
#include <linux/types.h>
#include <linux/kvm_types.h>
+#include <linux/jump_label.h>
+
#include <asm/kvm.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_mmio.h>
#include <asm/fpstate.h>
#include <kvm/arm_arch_timer.h>
+#include <asm/cputype.h>
#define __KVM_HAVE_ARCH_INTC_INITIALIZED
@@ -310,4 +313,14 @@ static inline int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu,
return -ENXIO;
}
+extern struct static_key_false kvm_gicv3_cpuif;
+
+static inline bool kvm_arm_support_gicv3_cpuif(void)
+{
+ if (IS_ENABLED(CONFIG_ARM_GIC_V3))
+ return !!cpuid_feature_extract(CPUID_EXT_PFR1, 28);
+ else
+ return false;
+}
+
#endif /* __ARM_KVM_HOST_H__ */
diff --git a/arch/arm/include/asm/kvm_hyp.h b/arch/arm/include/asm/kvm_hyp.h
index 6eaff28..bd9434e 100644
--- a/arch/arm/include/asm/kvm_hyp.h
+++ b/arch/arm/include/asm/kvm_hyp.h
@@ -23,8 +23,6 @@
#include <asm/kvm_mmu.h>
#include <asm/vfp.h>
-#define __hyp_text __section(.hyp.text) notrace
-
#define __ACCESS_CP15(CRn, Op1, CRm, Op2) \
"mrc", "mcr", __stringify(p15, Op1, %0, CRn, CRm, Op2), u32
#define __ACCESS_CP15_64(Op1, CRm) \
diff --git a/arch/arm/include/asm/virt.h b/arch/arm/include/asm/virt.h
index a2e75b8..e61a809 100644
--- a/arch/arm/include/asm/virt.h
+++ b/arch/arm/include/asm/virt.h
@@ -28,6 +28,9 @@
*/
#define BOOT_CPU_MODE_MISMATCH PSR_N_BIT
+#define __hyp_text __section(.hyp.text) notrace
+#define __hyp_data __section(.hyp.data)
+
#ifndef __ASSEMBLY__
#include <asm/cacheflush.h>
@@ -87,6 +90,11 @@ extern char __hyp_idmap_text_end[];
/* The section containing the hypervisor text */
extern char __hyp_text_start[];
extern char __hyp_text_end[];
+
+/* The section containing the hypervisor data */
+extern char __hyp_data_start[];
+extern char __hyp_data_end[];
+
#endif
#endif /* __ASSEMBLY__ */
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index d24e5dd..6d53824 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -25,6 +25,11 @@
*(.hyp.text) \
VMLINUX_SYMBOL(__hyp_text_end) = .;
+#define HYPERVISOR_DATA \
+ VMLINUX_SYMBOL(__hyp_data_start) = .; \
+ *(.hyp.data) \
+ VMLINUX_SYMBOL(__hyp_data_end) = .;
+
#define IDMAP_TEXT \
ALIGN_FUNCTION(); \
VMLINUX_SYMBOL(__idmap_text_start) = .; \
@@ -256,6 +261,7 @@ SECTIONS
*/
DATA_DATA
CONSTRUCTORS
+ HYPERVISOR_DATA
_edata = .;
}
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 75f130e..f966763 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -27,6 +27,7 @@
#include <linux/mman.h>
#include <linux/sched.h>
#include <linux/kvm.h>
+#include <linux/irqchip/arm-gic-v3.h>
#include <trace/events/kvm.h>
#include <kvm/arm_pmu.h>
@@ -68,6 +69,9 @@ static bool vgic_present;
static DEFINE_PER_CPU(unsigned char, kvm_arm_hardware_enabled);
+/* GIC system register CPU interface */
+__hyp_data DEFINE_STATIC_KEY_FALSE(kvm_gicv3_cpuif);
+
static void kvm_arm_set_running_vcpu(struct kvm_vcpu *vcpu)
{
BUG_ON(preemptible());
@@ -1178,6 +1182,14 @@ static int init_common_resources(void)
return -ENOMEM;
}
+ if (kvm_arm_support_gicv3_cpuif()) {
+ if (!gic_enable_sre())
+ kvm_info("GIC CPU interface present but disabled by higher exception level\n");
+
+ static_branch_enable(&kvm_gicv3_cpuif);
+ kvm_info("GIC system register CPU interface\n");
+ }
+
return 0;
}
@@ -1297,6 +1309,13 @@ static int init_hyp_mode(void)
goto out_err;
}
+ err = create_hyp_mappings(kvm_ksym_ref(__hyp_data_start),
+ kvm_ksym_ref(__hyp_data_end), PAGE_HYP);
+ if (err) {
+ kvm_err("Cannot map hyp data section\n");
+ goto out_err;
+ }
+
err = create_hyp_mappings(kvm_ksym_ref(__start_rodata),
kvm_ksym_ref(__end_rodata), PAGE_HYP_RO);
if (err) {
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 3eda975..1da74e8 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -24,6 +24,9 @@
#include <linux/types.h>
#include <linux/kvm_types.h>
+#include <linux/jump_label.h>
+
+#include <asm/cpufeature.h>
#include <asm/kvm.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_mmio.h>
@@ -390,4 +393,16 @@ static inline void __cpu_init_stage2(void)
"PARange is %d bits, unsupported configuration!", parange);
}
+extern struct static_key_false kvm_gicv3_cpuif;
+
+static inline bool kvm_arm_support_gicv3_cpuif(void)
+{
+ int reg = read_system_reg(SYS_ID_AA64PFR0_EL1);
+
+ if (IS_ENABLED(CONFIG_ARM_GIC_V3))
+ return !!cpuid_feature_extract_unsigned_field(reg, ID_AA64PFR0_GIC_SHIFT);
+
+ return false;
+}
+
#endif /* __ARM64_KVM_HOST_H__ */
diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index cff5105..5c4ac82 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -23,8 +23,6 @@
#include <asm/kvm_mmu.h>
#include <asm/sysreg.h>
-#define __hyp_text __section(.hyp.text) notrace
-
#define read_sysreg_elx(r,nvh,vh) \
({ \
u64 reg; \
diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
index 1788545..c49426e 100644
--- a/arch/arm64/include/asm/virt.h
+++ b/arch/arm64/include/asm/virt.h
@@ -42,6 +42,9 @@
#define BOOT_CPU_MODE_EL1 (0xe11)
#define BOOT_CPU_MODE_EL2 (0xe12)
+#define __hyp_text __section(.hyp.text) notrace
+#define __hyp_data __section(.hyp.data)
+
#ifndef __ASSEMBLY__
#include <asm/ptrace.h>
@@ -95,6 +98,10 @@ extern char __hyp_idmap_text_end[];
extern char __hyp_text_start[];
extern char __hyp_text_end[];
+/* The section containing the hypervisor data */
+extern char __hyp_data_start[];
+extern char __hyp_data_end[];
+
#endif /* __ASSEMBLY__ */
#endif /* ! __ASM__VIRT_H */
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 659963d..ea94a10 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -40,6 +40,11 @@ jiffies = jiffies_64;
*(.hyp.text) \
VMLINUX_SYMBOL(__hyp_text_end) = .;
+#define HYPERVISOR_DATA \
+ VMLINUX_SYMBOL(__hyp_data_start) = .; \
+ .hyp.data : {*(.hyp.data)} \
+ VMLINUX_SYMBOL(__hyp_data_end) = .;
+
#define IDMAP_TEXT \
. = ALIGN(SZ_4K); \
VMLINUX_SYMBOL(__idmap_text_start) = .; \
@@ -185,6 +190,7 @@ SECTIONS
_data = .;
_sdata = .;
RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
+ HYPERVISOR_DATA
PECOFF_EDATA_PADDING
_edata = .;
diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index 5a84b45..cdc1360 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -126,17 +126,13 @@ static void __hyp_text __deactivate_vm(struct kvm_vcpu *vcpu)
write_sysreg(0, vttbr_el2);
}
-static hyp_alternate_select(__vgic_call_save_state,
- __vgic_v2_save_state, __vgic_v3_save_state,
- ARM64_HAS_SYSREG_GIC_CPUIF);
-
-static hyp_alternate_select(__vgic_call_restore_state,
- __vgic_v2_restore_state, __vgic_v3_restore_state,
- ARM64_HAS_SYSREG_GIC_CPUIF);
-
static void __hyp_text __vgic_save_state(struct kvm_vcpu *vcpu)
{
- __vgic_call_save_state()(vcpu);
+ if (static_branch_unlikely(&kvm_gicv3_cpuif))
+ __vgic_v3_save_state(vcpu);
+ else
+ __vgic_v2_save_state(vcpu);
+
write_sysreg(read_sysreg(hcr_el2) & ~HCR_INT_OVERRIDE, hcr_el2);
}
@@ -149,7 +145,10 @@ static void __hyp_text __vgic_restore_state(struct kvm_vcpu *vcpu)
val |= vcpu->arch.irq_lines;
write_sysreg(val, hcr_el2);
- __vgic_call_restore_state()(vcpu);
+ if (static_branch_unlikely(&kvm_gicv3_cpuif))
+ __vgic_v3_restore_state(vcpu);
+ else
+ __vgic_v2_restore_state(vcpu);
}
static bool __hyp_text __true_value(void)
--
1.7.9.5
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