This patch tracks armv7 and armv8 fp/simd hardware state with cptr_el2 register.
On vcpu_load for 32 bit guests enable FP access, and enable fp/simd
trapping for 32 and 64 bit guests. On first fp/simd access trap to handler
to save host and restore guest context, and clear trapping bits to enable vcpu
lazy mode. On vcpu_put if trap bits are clear save guest and restore host
context and also save 32 bit guest fpexc register.
Signed-off-by: Mario Smarduch <m.smarduch@xxxxxxxxxxx>
---
arch/arm/include/asm/kvm_emulate.h | 5 ++
arch/arm/include/asm/kvm_host.h | 2 +
arch/arm/kvm/arm.c | 20 +++++--
arch/arm64/include/asm/kvm_asm.h | 2 +
arch/arm64/include/asm/kvm_emulate.h | 15 +++--
arch/arm64/include/asm/kvm_host.h | 16 +++++-
arch/arm64/kernel/asm-offsets.c | 1 +
arch/arm64/kvm/Makefile | 3 +-
arch/arm64/kvm/fpsimd_switch.S | 38 ++++++++++++
arch/arm64/kvm/hyp.S | 108 +++++++++++++----------------------
arch/arm64/kvm/hyp_head.S | 48 ++++++++++++++++
11 files changed, 181 insertions(+), 77 deletions(-)
create mode 100644 arch/arm64/kvm/fpsimd_switch.S
create mode 100644 arch/arm64/kvm/hyp_head.S
diff --git a/arch/arm/include/asm/kvm_emulate.h b/arch/arm/include/asm/kvm_emulate.h
index 3de11a2..13feed5 100644
--- a/arch/arm/include/asm/kvm_emulate.h
+++ b/arch/arm/include/asm/kvm_emulate.h
@@ -243,6 +243,11 @@ static inline unsigned long vcpu_data_host_to_guest(struct kvm_vcpu *vcpu,
}
}
+static inline bool kvm_guest_vcpu_is_32bit(struct kvm_vcpu *vcpu)
+{
+ return true;
+}
+
#ifdef CONFIG_VFPv3
/* Called from vcpu_load - save fpexc and enable guest access to fp/simd unit */
static inline void kvm_enable_vcpu_fpexc(struct kvm_vcpu *vcpu)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index ecc883a..720ae51 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -227,6 +227,8 @@ int kvm_perf_teardown(void);
void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
+
+static inline void kvm_save_guest_vcpu_fpexc(struct kvm_vcpu *vcpu) {}
void kvm_restore_host_vfp_state(struct kvm_vcpu *);
static inline void kvm_arch_hardware_disable(void) {}
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 1de07ab..dd59f8a 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -292,8 +292,12 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
kvm_arm_set_running_vcpu(vcpu);
- /* Save and enable FPEXC before we load guest context */
- kvm_enable_vcpu_fpexc(vcpu);
+ /*
+ * For 32bit guest executing on arm64, enable fp/simd access in
+ * EL2. On arm32 save host fpexc and then enable fp/simd access.
+ */
+ if (kvm_guest_vcpu_is_32bit(vcpu))
+ kvm_enable_vcpu_fpexc(vcpu);
/* reset hyp cptr register to trap on tracing and vfp/simd access*/
vcpu_reset_cptr(vcpu);
@@ -302,10 +306,18 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
/* If the fp/simd registers are dirty save guest, restore host. */
- if (kvm_vcpu_vfp_isdirty(vcpu))
+ if (kvm_vcpu_vfp_isdirty(vcpu)) {
kvm_restore_host_vfp_state(vcpu);
- /* Restore host FPEXC trashed in vcpu_load */
+ /*
+ * For 32bit guest on arm64 save the guest fpexc register
+ * in EL2 mode.
+ */
+ if (kvm_guest_vcpu_is_32bit(vcpu))
+ kvm_save_guest_vcpu_fpexc(vcpu);
+ }
+
+ /* For arm32 restore host FPEXC trashed in vcpu_load. */
kvm_restore_host_fpexc(vcpu);
/*
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 5e37710..d53d069 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -117,6 +117,8 @@ extern char __kvm_hyp_vector[];
extern void __kvm_flush_vm_context(void);
extern void __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa);
extern void __kvm_tlb_flush_vmid(struct kvm *kvm);
+extern void __kvm_vcpu_enable_fpexc32(void);
+extern void __kvm_vcpu_save_fpexc32(struct kvm_vcpu *vcpu);
extern int __kvm_vcpu_run(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 8dccbd7..bbbee9d 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -290,13 +290,20 @@ static inline unsigned long vcpu_data_host_to_guest(struct kvm_vcpu *vcpu,
return data; /* Leave LE untouched */
}
-static inline void kvm_enable_vcpu_fpexc(struct kvm_vcpu *vcpu) {}
-static inline void kvm_restore_host_fpexc(struct kvm_vcpu *vcpu) {}
-static inline void vcpu_reset_cptr(struct kvm_vcpu *vcpu) {}
+static inline bool kvm_guest_vcpu_is_32bit(struct kvm_vcpu *vcpu)
+{
+ return !(vcpu->arch.hcr_el2 & HCR_RW);
+}
+
+static inline void vcpu_reset_cptr(struct kvm_vcpu *vcpu)
+{
+ vcpu->arch.cptr_el2 = CPTR_EL2_TTA | CPTR_EL2_TFP;
+}
+
static inline bool kvm_vcpu_vfp_isdirty(struct kvm_vcpu *vcpu)
{
- return false;
+ return !!(~vcpu->arch.cptr_el2 & CPTR_EL2_TFP);
}
#endif /* __ARM64_KVM_EMULATE_H__ */
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e16fd39..0c65393 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -100,6 +100,7 @@ struct kvm_vcpu_arch {
/* HYP configuration */
u64 hcr_el2;
u32 mdcr_el2;
+ u32 cptr_el2;
/* Exception Information */
struct kvm_vcpu_fault_info fault;
@@ -248,7 +249,20 @@ static inline void kvm_arch_hardware_unsetup(void) {}
static inline void kvm_arch_sync_events(struct kvm *kvm) {}
static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
-static inline void kvm_restore_host_vfp_state(struct kvm_vcpu *vcpu) {}
+
+static inline void kvm_enable_vcpu_fpexc(struct kvm_vcpu *vcpu)
+{
+ /* Enable FP/SIMD access from EL2 mode*/
+ kvm_call_hyp(__kvm_vcpu_enable_fpexc32);
+}
+
+static inline void kvm_save_guest_vcpu_fpexc(struct kvm_vcpu *vcpu)
+{
+ /* Save FPEXEC32_EL2 in EL2 mode */
+ kvm_call_hyp(__kvm_vcpu_save_fpexc32, vcpu);
+}
+static inline void kvm_restore_host_fpexc(struct kvm_vcpu *vcpu) {}
+void kvm_restore_host_vfp_state(struct kvm_vcpu *vcpu);
void kvm_arm_init_debug(void);
void kvm_arm_setup_debug(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 8d89cf8..3c8d836 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -123,6 +123,7 @@ int main(void)
DEFINE(DEBUG_WVR, offsetof(struct kvm_guest_debug_arch, dbg_wvr));
DEFINE(VCPU_HCR_EL2, offsetof(struct kvm_vcpu, arch.hcr_el2));
DEFINE(VCPU_MDCR_EL2, offsetof(struct kvm_vcpu, arch.mdcr_el2));
+ DEFINE(VCPU_CPTR_EL2, offsetof(struct kvm_vcpu, arch.cptr_el2));
DEFINE(VCPU_IRQ_LINES, offsetof(struct kvm_vcpu, arch.irq_lines));
DEFINE(VCPU_HOST_CONTEXT, offsetof(struct kvm_vcpu, arch.host_cpu_context));
DEFINE(VCPU_HOST_DEBUG_STATE, offsetof(struct kvm_vcpu, arch.host_debug_state));
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 1949fe5..262b9a5 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -17,7 +17,8 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(ARM)/psci.o $(ARM)/perf.o
kvm-$(CONFIG_KVM_ARM_HOST) += emulate.o inject_fault.o regmap.o
kvm-$(CONFIG_KVM_ARM_HOST) += hyp.o hyp-init.o handle_exit.o
-kvm-$(CONFIG_KVM_ARM_HOST) += guest.o debug.o reset.o sys_regs.o sys_regs_generic_v8.o
+kvm-$(CONFIG_KVM_ARM_HOST) += guest.o debug.o reset.o sys_regs.o
+kvm-$(CONFIG_KVM_ARM_HOST) += sys_regs_generic_v8.o fpsimd_switch.o
kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic.o
kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic-v2.o
diff --git a/arch/arm64/kvm/fpsimd_switch.S b/arch/arm64/kvm/fpsimd_switch.S
new file mode 100644
index 0000000..5295512
--- /dev/null
+++ b/arch/arm64/kvm/fpsimd_switch.S
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2012,2013 - ARM Ltd
+ * Author: Marc Zyngier <marc.zyngier@xxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+
+#include "hyp_head.S"
+
+ .text
+/**
+ * void kvm_restore_host_vfp_state(struct vcpu *vcpu) -
+ * This function saves the guest, restores host, called from host.
+ */
+ENTRY(kvm_restore_host_vfp_state)
+ push xzr, lr
+
+ add x2, x0, #VCPU_CONTEXT
+ bl __save_fpsimd
+
+ ldr x2, [x0, #VCPU_HOST_CONTEXT]
+ bl __restore_fpsimd
+
+ pop xzr, lr
+ ret
+ENDPROC(kvm_restore_host_vfp_state)
diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index e583613..b8b1afb 100644
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -17,23 +17,7 @@
#include <linux/linkage.h>
-#include <asm/alternative.h>
-#include <asm/asm-offsets.h>
-#include <asm/assembler.h>
-#include <asm/cpufeature.h>
-#include <asm/debug-monitors.h>
-#include <asm/esr.h>
-#include <asm/fpsimdmacros.h>
-#include <asm/kvm.h>
-#include <asm/kvm_arm.h>
-#include <asm/kvm_asm.h>
-#include <asm/kvm_mmu.h>
-#include <asm/memory.h>
-
-#define CPU_GP_REG_OFFSET(x) (CPU_GP_REGS + x)
-#define CPU_XREG_OFFSET(x) CPU_GP_REG_OFFSET(CPU_USER_PT_REGS + 8*x)
-#define CPU_SPSR_OFFSET(x) CPU_GP_REG_OFFSET(CPU_SPSR + 8*x)
-#define CPU_SYSREG_OFFSET(x) (CPU_SYSREGS + 8*x)
+#include "hyp_head.S"
.text
.pushsection .hyp.text, "ax"
@@ -104,20 +88,6 @@
restore_common_regs
.endm
-.macro save_fpsimd
- // x2: cpu context address
- // x3, x4: tmp regs
- add x3, x2, #CPU_GP_REG_OFFSET(CPU_FP_REGS)
- fpsimd_save x3, 4
-.endm
-
-.macro restore_fpsimd
- // x2: cpu context address
- // x3, x4: tmp regs
- add x3, x2, #CPU_GP_REG_OFFSET(CPU_FP_REGS)
- fpsimd_restore x3, 4
-.endm
-
.macro save_guest_regs
// x0 is the vcpu address
// x1 is the return code, do not corrupt!
@@ -385,14 +355,6 @@
tbz \tmp, #KVM_ARM64_DEBUG_DIRTY_SHIFT, \target
.endm
-/*
- * Branch to target if CPTR_EL2.TFP bit is set (VFP/SIMD trapping enabled)
- */
-.macro skip_fpsimd_state tmp, target
- mrs \tmp, cptr_el2
- tbnz \tmp, #CPTR_EL2_TFP_SHIFT, \target
-.endm
-
.macro compute_debug_state target
// Compute debug state: If any of KDE, MDE or KVM_ARM64_DEBUG_DIRTY
// is set, we do a full save/restore cycle and disable trapping.
@@ -433,10 +395,6 @@
mrs x5, ifsr32_el2
stp x4, x5, [x3]
- skip_fpsimd_state x8, 2f
- mrs x6, fpexc32_el2
- str x6, [x3, #16]
-2:
skip_debug_state x8, 1f
mrs x7, dbgvcr32_el2
str x7, [x3, #24]
@@ -467,22 +425,9 @@
.macro activate_traps
ldr x2, [x0, #VCPU_HCR_EL2]
-
- /*
- * We are about to set CPTR_EL2.TFP to trap all floating point
- * register accesses to EL2, however, the ARM ARM clearly states that
- * traps are only taken to EL2 if the operation would not otherwise
- * trap to EL1. Therefore, always make sure that for 32-bit guests,
- * we set FPEXC.EN to prevent traps to EL1, when setting the TFP bit.
- */
- tbnz x2, #HCR_RW_SHIFT, 99f // open code skip_32bit_state
- mov x3, #(1 << 30)
- msr fpexc32_el2, x3
- isb
-99:
msr hcr_el2, x2
- mov x2, #CPTR_EL2_TTA
- orr x2, x2, #CPTR_EL2_TFP
+
+ ldr w2, [x0, VCPU_CPTR_EL2]
msr cptr_el2, x2
mov x2, #(1 << 15) // Trap CP15 Cr=15
@@ -668,15 +613,15 @@ __restore_debug:
ret
-__save_fpsimd:
- skip_fpsimd_state x3, 1f
+ENTRY(__save_fpsimd)
save_fpsimd
-1: ret
+ ret
+ENDPROC(__save_fpsimd)
-__restore_fpsimd:
- skip_fpsimd_state x3, 1f
+ENTRY(__restore_fpsimd)
restore_fpsimd
-1: ret
+ ret
+ENDPROC(__restore_fpsimd)
switch_to_guest_fpsimd:
push x4, lr
@@ -763,7 +708,6 @@ __kvm_vcpu_return:
add x2, x0, #VCPU_CONTEXT
save_guest_regs
- bl __save_fpsimd
bl __save_sysregs
skip_debug_state x3, 1f
@@ -784,8 +728,10 @@ __kvm_vcpu_return:
kern_hyp_va x2
bl __restore_sysregs
- bl __restore_fpsimd
- /* Clear FPSIMD and Trace trapping */
+
+ /* Save CPTR_EL2 between exits and clear FPSIMD and Trace trapping */
+ mrs x3, cptr_el2
+ str w3, [x0, VCPU_CPTR_EL2]
msr cptr_el2, xzr
skip_debug_state x3, 1f
@@ -863,6 +809,34 @@ ENTRY(__kvm_flush_vm_context)
ret
ENDPROC(__kvm_flush_vm_context)
+/**
+ * void __kvm_enable_fpexc32(void) -
+ * We may be entering the guest and set CPTR_EL2.TFP to trap all floating
+ * point register accesses to EL2, however, the ARM manual clearly states
+ * that traps are only taken to EL2 if the operation would not otherwise
+ * trap to EL1. Therefore, always make sure that for 32-bit guests,
+ * we set FPEXC.EN to prevent traps to EL1, when setting the TFP bit.
+ */
+ENTRY(__kvm_vcpu_enable_fpexc32)
+ mov x3, #(1 << 30)
+ msr fpexc32_el2, x3
+ isb
+ ret
+ENDPROC(__kvm_vcpu_enable_fpexc32)
+
+/**
+ * void __kvm_save_fpexc32(void) -
+ * This function restores guest FPEXC to its vcpu context, we call this
+ * function from vcpu_put.
+ */
+ENTRY(__kvm_vcpu_save_fpexc32)
+ kern_hyp_va x0
+ add x2, x0, #VCPU_CONTEXT
+ mrs x1, fpexc32_el2
+ str x1, [x2, #CPU_SYSREG_OFFSET(FPEXC32_EL2)]
+ ret
+ENDPROC(__kvm_vcpu_save_fpexc32)
+
__kvm_hyp_panic:
// Guess the context by looking at VTTBR:
// If zero, then we're already a host.
diff --git a/arch/arm64/kvm/hyp_head.S b/arch/arm64/kvm/hyp_head.S
new file mode 100644
index 0000000..bb32824
--- /dev/null
+++ b/arch/arm64/kvm/hyp_head.S
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2012,2013 - ARM Ltd
+ * Author: Marc Zyngier <marc.zyngier@xxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <asm/alternative.h>
+#include <asm/asm-offsets.h>
+#include <asm/assembler.h>
+#include <asm/cpufeature.h>
+#include <asm/debug-monitors.h>
+#include <asm/esr.h>
+#include <asm/fpsimdmacros.h>
+#include <asm/kvm.h>
+#include <asm/kvm_arm.h>
+#include <asm/kvm_asm.h>
+#include <asm/kvm_mmu.h>
+#include <asm/memory.h>
+
+#define CPU_GP_REG_OFFSET(x) (CPU_GP_REGS + x)
+#define CPU_XREG_OFFSET(x) CPU_GP_REG_OFFSET(CPU_USER_PT_REGS + 8*x)
+#define CPU_SPSR_OFFSET(x) CPU_GP_REG_OFFSET(CPU_SPSR + 8*x)
+#define CPU_SYSREG_OFFSET(x) (CPU_SYSREGS + 8*x)
+
+.macro save_fpsimd
+ // x2: cpu context address
+ // x3, x4: tmp regs
+ add x3, x2, #CPU_GP_REG_OFFSET(CPU_FP_REGS)
+ fpsimd_save x3, 4
+.endm
+
+.macro restore_fpsimd
+ // x2: cpu context address
+ // x3, x4: tmp regs
+ add x3, x2, #CPU_GP_REG_OFFSET(CPU_FP_REGS)
+ fpsimd_restore x3, 4
+.endm
--
1.9.1
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