Enable armv7 enhanced fp/simd context switch. Guest and host registers are only
context switched on first access and vcpu put.
Signed-off-by: Mario Smarduch <m.smarduch@xxxxxxxxxxx>
---
arch/arm/include/asm/kvm_host.h | 2 ++
arch/arm/kernel/asm-offsets.c | 1 +
arch/arm/kvm/arm.c | 10 +++++++++
arch/arm/kvm/interrupts.S | 43 ++++++++++++++-------------------------
arch/arm64/include/asm/kvm_host.h | 2 ++
5 files changed, 30 insertions(+), 28 deletions(-)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index d3ef58a..90f7f59 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -238,6 +238,8 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
+void vcpu_restore_host_vfp_state(struct kvm_vcpu *);
+
static inline void kvm_arch_hardware_disable(void) {}
static inline void kvm_arch_hardware_unsetup(void) {}
static inline void kvm_arch_sync_events(struct kvm *kvm) {}
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index 871b826..395ecca 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -185,6 +185,7 @@ int main(void)
DEFINE(VCPU_PC, offsetof(struct kvm_vcpu, arch.regs.usr_regs.ARM_pc));
DEFINE(VCPU_CPSR, offsetof(struct kvm_vcpu, arch.regs.usr_regs.ARM_cpsr));
DEFINE(VCPU_HCR, offsetof(struct kvm_vcpu, arch.hcr));
+ DEFINE(VCPU_HCPTR, offsetof(struct kvm_vcpu, arch.hcptr));
DEFINE(VCPU_IRQ_LINES, offsetof(struct kvm_vcpu, arch.irq_lines));
DEFINE(VCPU_HSR, offsetof(struct kvm_vcpu, arch.fault.hsr));
DEFINE(VCPU_HxFAR, offsetof(struct kvm_vcpu, arch.fault.hxfar));
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index dda1959..b16ed98 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -308,10 +308,20 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
vcpu->arch.host_cpu_context = this_cpu_ptr(kvm_host_cpu_state);
kvm_arm_set_running_vcpu(vcpu);
+
+ /* Save and enable fpexc, and enable default traps */
+ vcpu_trap_vfp_enable(vcpu);
}
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
+ /* If the fp/simd registers are dirty save guest, restore host. */
+ if (vcpu_vfp_isdirty(vcpu))
+ vcpu_restore_host_vfp_state(vcpu);
+
+ /* Restore host FPEXC trashed in vcpu_load */
+ vcpu_restore_host_fpexc(vcpu);
+
/*
* The arch-generic KVM code expects the cpu field of a vcpu to be -1
* if the vcpu is no longer assigned to a cpu. This is used for the
diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S
index 900ef6d..245c11f 100644
--- a/arch/arm/kvm/interrupts.S
+++ b/arch/arm/kvm/interrupts.S
@@ -116,22 +116,15 @@ ENTRY(__kvm_vcpu_run)
read_cp15_state store_to_vcpu = 0
write_cp15_state read_from_vcpu = 1
- @ If the host kernel has not been configured with VFPv3 support,
- @ then it is safer if we deny guests from using it as well.
-#ifdef CONFIG_VFPv3
- @ Set FPEXC_EN so the guest doesn't trap floating point instructions
- VFPFMRX r2, FPEXC @ VMRS
- push {r2}
- orr r2, r2, #FPEXC_EN
- VFPFMXR FPEXC, r2 @ VMSR
-#endif
+ @ Configure trapping of access to tracing and fp/simd registers
+ ldr r1, [vcpu, #VCPU_HCPTR]
+ mcr p15, 4, r1, c1, c1, 2
@ Configure Hyp-role
configure_hyp_role vmentry
@ Trap coprocessor CRx accesses
set_hstr vmentry
- set_hcptr vmentry, (HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11))
set_hdcr vmentry
@ Write configured ID register into MIDR alias
@@ -170,23 +163,10 @@ __kvm_vcpu_return:
@ Don't trap coprocessor accesses for host kernel
set_hstr vmexit
set_hdcr vmexit
- set_hcptr vmexit, (HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11)), after_vfp_restore
-#ifdef CONFIG_VFPv3
- @ Switch VFP/NEON hardware state to the host's
- add r7, vcpu, #VCPU_VFP_GUEST
- store_vfp_state r7
- add r7, vcpu, #VCPU_VFP_HOST
- ldr r7, [r7]
- restore_vfp_state r7
-
-after_vfp_restore:
- @ Restore FPEXC_EN which we clobbered on entry
- pop {r2}
- VFPFMXR FPEXC, r2
-#else
-after_vfp_restore:
-#endif
+ @ Disable trace and fp/simd traps
+ mov r2, #0
+ mcr p15, 4, r2, c1, c1, 2
@ Reset Hyp-role
configure_hyp_role vmexit
@@ -482,8 +462,15 @@ guest_trap:
switch_to_guest_vfp:
push {r3-r7}
- @ NEON/VFP used. Turn on VFP access.
- set_hcptr vmtrap, (HCPTR_TCP(10) | HCPTR_TCP(11))
+ @ fp/simd was accessed, so disable trapping and save hcptr register
+ @ which is used across exits until next vcpu_load.
+ mrc p15, 4, r2, c1, c1, 2
+ mov r3, #(HCPTR_TCP(10) | HCPTR_TCP(11))
+ bic r3, r2, r3
+ mcr p15, 4, r3, c1, c1, 2
+ str r3, [vcpu, #VCPU_HCPTR]
+
+ isb
@ Switch VFP/NEON hardware state to the guest's
add r7, r0, #VCPU_VFP_HOST
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 689d4c9..bfe4d4e 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -338,6 +338,8 @@ 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 vcpu_restore_host_vfp_state(struct kvm_vcpu *vcpu) {}
+
void kvm_arm_init_debug(void);
void kvm_arm_setup_debug(struct kvm_vcpu *vcpu);
void kvm_arm_clear_debug(struct kvm_vcpu *vcpu);
--
1.9.1
--
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