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ARM: KVM: Add VFP save/restore

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This is almost a copy/paste of the existing version, with a couple
of subtle differences:
- Only write to FPEXC once on the save path
- Add an isb when enabling VFP access

The patch also defines a few sysreg accessors and a __vfp_enabled
predicate that test the VFP trapping state.

Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Marc Zyngier 2016-01-04 15:41:51 +00:00
parent c0c2cdbffe
commit 59cbcdb5d8
3 changed files with 82 additions and 0 deletions
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1
arch/arm/kvm/hyp/Makefile
View File

@ -6,3 +6,4 @@ obj-$(CONFIG_KVM_ARM_HOST) += tlb.o
obj-$(CONFIG_KVM_ARM_HOST) += cp15-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += timer-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += vgic-v2-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += vfp.o

13
arch/arm/kvm/hyp/hyp.h
View File

@ -21,6 +21,7 @@
#include <linux/compiler.h>
#include <linux/kvm_host.h>
#include <asm/kvm_mmu.h>
#include <asm/vfp.h>
#define __hyp_text __section(.hyp.text) notrace
@ -31,6 +32,8 @@
"mrc", "mcr", __stringify(p15, Op1, %0, CRn, CRm, Op2), u32
#define __ACCESS_CP15_64(Op1, CRm) \
"mrrc", "mcrr", __stringify(p15, Op1, %Q0, %R0, CRm), u64
#define __ACCESS_VFP(CRn) \
"mrc", "mcr", __stringify(p10, 7, %0, CRn, cr0, 0), u32
#define __write_sysreg(v, r, w, c, t) asm volatile(w " " c : : "r" ((t)(v)))
#define write_sysreg(v, ...) __write_sysreg(v, __VA_ARGS__)
@ -53,6 +56,7 @@
#define VMPIDR __ACCESS_CP15(c0, 4, c0, 5)
#define SCTLR __ACCESS_CP15(c1, 0, c0, 0)
#define CPACR __ACCESS_CP15(c1, 0, c0, 2)
#define HCPTR __ACCESS_CP15(c1, 4, c1, 2)
#define TTBCR __ACCESS_CP15(c2, 0, c0, 2)
#define DACR __ACCESS_CP15(c3, 0, c0, 0)
#define DFSR __ACCESS_CP15(c5, 0, c0, 0)
@ -77,6 +81,8 @@
#define CNTV_CTL __ACCESS_CP15(c14, 0, c3, 1)
#define CNTHCTL __ACCESS_CP15(c14, 4, c1, 0)
#define VFP_FPEXC __ACCESS_VFP(FPEXC)
void __timer_save_state(struct kvm_vcpu *vcpu);
void __timer_restore_state(struct kvm_vcpu *vcpu);
@ -86,4 +92,11 @@ void __vgic_v2_restore_state(struct kvm_vcpu *vcpu);
void __sysreg_save_state(struct kvm_cpu_context *ctxt);
void __sysreg_restore_state(struct kvm_cpu_context *ctxt);
void asmlinkage __vfp_save_state(struct vfp_hard_struct *vfp);
void asmlinkage __vfp_restore_state(struct vfp_hard_struct *vfp);
static inline bool __vfp_enabled(void)
{
return !(read_sysreg(HCPTR) & (HCPTR_TCP(11) | HCPTR_TCP(10)));
}
#endif /* __ARM_KVM_HYP_H__ */

68
arch/arm/kvm/hyp/vfp.S Normal file
View File

@ -0,0 +1,68 @@
/*
* Copyright (C) 2012 - Virtual Open Systems and Columbia University
* Author: Christoffer Dall <c.dall@virtualopensystems.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 <linux/linkage.h>
#include <asm/vfpmacros.h>
.text
.pushsection .hyp.text, "ax"
/* void __vfp_save_state(struct vfp_hard_struct *vfp); */
ENTRY(__vfp_save_state)
push {r4, r5}
VFPFMRX r1, FPEXC
@ Make sure *really* VFP is enabled so we can touch the registers.
orr r5, r1, #FPEXC_EN
tst r5, #FPEXC_EX @ Check for VFP Subarchitecture
bic r5, r5, #FPEXC_EX @ FPEXC_EX disable
VFPFMXR FPEXC, r5
isb
VFPFMRX r2, FPSCR
beq 1f
@ If FPEXC_EX is 0, then FPINST/FPINST2 reads are upredictable, so
@ we only need to save them if FPEXC_EX is set.
VFPFMRX r3, FPINST
tst r5, #FPEXC_FP2V
VFPFMRX r4, FPINST2, ne @ vmrsne
1:
VFPFSTMIA r0, r5 @ Save VFP registers
stm r0, {r1-r4} @ Save FPEXC, FPSCR, FPINST, FPINST2
pop {r4, r5}
bx lr
ENDPROC(__vfp_save_state)
/* void __vfp_restore_state(struct vfp_hard_struct *vfp);
* Assume FPEXC_EN is on and FPEXC_EX is off */
ENTRY(__vfp_restore_state)
VFPFLDMIA r0, r1 @ Load VFP registers
ldm r0, {r0-r3} @ Load FPEXC, FPSCR, FPINST, FPINST2
VFPFMXR FPSCR, r1
tst r0, #FPEXC_EX @ Check for VFP Subarchitecture
beq 1f
VFPFMXR FPINST, r2
tst r0, #FPEXC_FP2V
VFPFMXR FPINST2, r3, ne
1:
VFPFMXR FPEXC, r0 @ FPEXC (last, in case !EN)
bx lr
ENDPROC(__vfp_restore_state)
.popsection