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From: Christoffer Dall <christoffer.dall@linaro.org>
To: Mario Smarduch <m.smarduch@samsung.com>
Cc: marc.zyngier@arm.com, kvmarm@lists.cs.columbia.edu,
	kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 3/3] KVM/arm/arm64: enable enhanced armv8 fp/simd lazy switch
Date: Sat, 19 Dec 2015 08:45:38 +0100	[thread overview]
Message-ID: <20151219074538.GA9370@cbox> (raw)
In-Reply-To: <5674B00C.1050900@samsung.com>

On Fri, Dec 18, 2015 at 05:17:00PM -0800, Mario Smarduch wrote:
> On 12/18/2015 5:54 AM, Christoffer Dall wrote:
> > On Sun, Dec 06, 2015 at 05:07:14PM -0800, Mario Smarduch wrote:
> >> 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@samsung.com>
> >> ---
> >>  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@arm.com>
> >> + *
> > 
> > Is this copied code or new code?
> 
> It's mostly refactored copied code.

Then it's probably fine to keep the original copyright.

> > 
> >> + * 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
> > 
> > this is only called via a hypercall so do you really need the ISB?
> 
> Same comment as in 2nd patch for the isb.
> 

Unless you can argue that something needs to take effect before
something else, where there's no other implicit barrier, you don't need
the 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@arm.com>
> >> + *
> >> + * 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
> >>
> > 
> > I'm not going to review the details of this, since we have to rebase it
> > on the world-switch in C, sorry.
> That fine.
> > 
> > The good news is that it should be much simpler to write in C-code.
> > 
> > Let me know if you don't have the bandwidth to rebase this, in that case
> > I'll be happy to help.
> 
> Let me see where I'm at by the end of Monday, if there is a rush to get it into
> next release by all means.
> 
Sounds good - I prefer having you do it ;)

-Christoffer

WARNING: multiple messages have this Message-ID
From: christoffer.dall@linaro.org (Christoffer Dall)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v5 3/3] KVM/arm/arm64: enable enhanced armv8 fp/simd lazy switch
Date: Sat, 19 Dec 2015 08:45:38 +0100	[thread overview]
Message-ID: <20151219074538.GA9370@cbox> (raw)
In-Reply-To: <5674B00C.1050900@samsung.com>

On Fri, Dec 18, 2015 at 05:17:00PM -0800, Mario Smarduch wrote:
> On 12/18/2015 5:54 AM, Christoffer Dall wrote:
> > On Sun, Dec 06, 2015 at 05:07:14PM -0800, Mario Smarduch wrote:
> >> 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@samsung.com>
> >> ---
> >>  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@arm.com>
> >> + *
> > 
> > Is this copied code or new code?
> 
> It's mostly refactored copied code.

Then it's probably fine to keep the original copyright.

> > 
> >> + * 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
> > 
> > this is only called via a hypercall so do you really need the ISB?
> 
> Same comment as in 2nd patch for the isb.
> 

Unless you can argue that something needs to take effect before
something else, where there's no other implicit barrier, you don't need
the 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@arm.com>
> >> + *
> >> + * 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
> >>
> > 
> > I'm not going to review the details of this, since we have to rebase it
> > on the world-switch in C, sorry.
> That fine.
> > 
> > The good news is that it should be much simpler to write in C-code.
> > 
> > Let me know if you don't have the bandwidth to rebase this, in that case
> > I'll be happy to help.
> 
> Let me see where I'm at by the end of Monday, if there is a rush to get it into
> next release by all means.
> 
Sounds good - I prefer having you do it ;)

-Christoffer

  reply	other threads:[~2015-12-19  7:45 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-07  1:07 [PATCH v5 0/3] KVM/arm/arm64: enhance armv7/8 " Mario Smarduch
2015-12-07  1:07 ` Mario Smarduch
2015-12-07  1:07 ` [PATCH v5 1/3] KVM/arm: add hooks for armv7 fp/simd lazy switch support Mario Smarduch
2015-12-07  1:07   ` Mario Smarduch
2015-12-18 13:07   ` Christoffer Dall
2015-12-18 13:07     ` Christoffer Dall
2015-12-18 22:27     ` Mario Smarduch
2015-12-18 22:27       ` Mario Smarduch
2015-12-07  1:07 ` [PATCH v5 2/3] KVM/arm/arm64: enable enhanced armv7 fp/simd lazy switch Mario Smarduch
2015-12-07  1:07   ` Mario Smarduch
2015-12-18 13:49   ` Christoffer Dall
2015-12-18 13:49     ` Christoffer Dall
2015-12-19  0:54     ` Mario Smarduch
2015-12-19  0:54       ` Mario Smarduch
2015-12-07  1:07 ` [PATCH v5 3/3] KVM/arm/arm64: enable enhanced armv8 " Mario Smarduch
2015-12-07  1:07   ` Mario Smarduch
2015-12-18 13:54   ` Christoffer Dall
2015-12-18 13:54     ` Christoffer Dall
2015-12-19  1:17     ` Mario Smarduch
2015-12-19  1:17       ` Mario Smarduch
2015-12-19  7:45       ` Christoffer Dall [this message]
2015-12-19  7:45         ` Christoffer Dall
2015-12-21 19:34         ` Mario Smarduch
2015-12-21 19:34           ` Mario Smarduch
2015-12-22  8:06           ` Christoffer Dall
2015-12-22  8:06             ` Christoffer Dall
2015-12-22 18:01             ` Mario Smarduch
2015-12-22 18:01               ` Mario Smarduch

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