tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
ARM: KVM: Add VFP save/restore
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>
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+1
arch/arm/kvm/hyp/Makefile
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arch/arm/kvm/hyp/Makefile
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arch/arm/kvm/hyp/hyp.h
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arch/arm/kvm/hyp/hyp.h
···
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#include <linux/compiler.h>
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#include <linux/kvm_host.h>
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#include <asm/kvm_mmu.h>
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#include <asm/vfp.h>
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#define __hyp_text __section(.hyp.text) notrace
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···
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"mrc", "mcr", __stringify(p15, Op1, %0, CRn, CRm, Op2), u32
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#define __ACCESS_CP15_64(Op1, CRm) \
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"mrrc", "mcrr", __stringify(p15, Op1, %Q0, %R0, CRm), u64
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#define __ACCESS_VFP(CRn) \
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"mrc", "mcr", __stringify(p10, 7, %0, CRn, cr0, 0), u32
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#define __write_sysreg(v, r, w, c, t) asm volatile(w " " c : : "r" ((t)(v)))
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#define write_sysreg(v, ...) __write_sysreg(v, __VA_ARGS__)
···
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#define VMPIDR __ACCESS_CP15(c0, 4, c0, 5)
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#define SCTLR __ACCESS_CP15(c1, 0, c0, 0)
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#define CPACR __ACCESS_CP15(c1, 0, c0, 2)
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#define HCPTR __ACCESS_CP15(c1, 4, c1, 2)
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#define TTBCR __ACCESS_CP15(c2, 0, c0, 2)
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#define DACR __ACCESS_CP15(c3, 0, c0, 0)
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#define DFSR __ACCESS_CP15(c5, 0, c0, 0)
···
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#define CNTV_CTL __ACCESS_CP15(c14, 0, c3, 1)
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#define CNTHCTL __ACCESS_CP15(c14, 4, c1, 0)
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#define VFP_FPEXC __ACCESS_VFP(FPEXC)
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void __timer_save_state(struct kvm_vcpu *vcpu);
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void __timer_restore_state(struct kvm_vcpu *vcpu);
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···
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void __sysreg_save_state(struct kvm_cpu_context *ctxt);
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void __sysreg_restore_state(struct kvm_cpu_context *ctxt);
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void asmlinkage __vfp_save_state(struct vfp_hard_struct *vfp);
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void asmlinkage __vfp_restore_state(struct vfp_hard_struct *vfp);
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static inline bool __vfp_enabled(void)
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{
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return !(read_sysreg(HCPTR) & (HCPTR_TCP(11) | HCPTR_TCP(10)));
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}
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#endif /* __ARM_KVM_HYP_H__ */
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arch/arm/kvm/hyp/vfp.S
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arch/arm/kvm/hyp/vfp.S
···
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/*
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* Copyright (C) 2012 - Virtual Open Systems and Columbia University
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* Author: Christoffer Dall <c.dall@virtualopensystems.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/linkage.h>
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#include <asm/vfpmacros.h>
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.text
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.pushsection .hyp.text, "ax"
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/* void __vfp_save_state(struct vfp_hard_struct *vfp); */
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ENTRY(__vfp_save_state)
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push {r4, r5}
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VFPFMRX r1, FPEXC
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@ Make sure *really* VFP is enabled so we can touch the registers.
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orr r5, r1, #FPEXC_EN
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tst r5, #FPEXC_EX @ Check for VFP Subarchitecture
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bic r5, r5, #FPEXC_EX @ FPEXC_EX disable
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VFPFMXR FPEXC, r5
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isb
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VFPFMRX r2, FPSCR
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beq 1f
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@ If FPEXC_EX is 0, then FPINST/FPINST2 reads are upredictable, so
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@ we only need to save them if FPEXC_EX is set.
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VFPFMRX r3, FPINST
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tst r5, #FPEXC_FP2V
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VFPFMRX r4, FPINST2, ne @ vmrsne
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1:
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VFPFSTMIA r0, r5 @ Save VFP registers
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stm r0, {r1-r4} @ Save FPEXC, FPSCR, FPINST, FPINST2
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pop {r4, r5}
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bx lr
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ENDPROC(__vfp_save_state)
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/* void __vfp_restore_state(struct vfp_hard_struct *vfp);
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* Assume FPEXC_EN is on and FPEXC_EX is off */
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ENTRY(__vfp_restore_state)
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VFPFLDMIA r0, r1 @ Load VFP registers
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ldm r0, {r0-r3} @ Load FPEXC, FPSCR, FPINST, FPINST2
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VFPFMXR FPSCR, r1
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tst r0, #FPEXC_EX @ Check for VFP Subarchitecture
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beq 1f
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VFPFMXR FPINST, r2
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tst r0, #FPEXC_FP2V
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VFPFMXR FPINST2, r3, ne
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1:
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VFPFMXR FPEXC, r0 @ FPEXC (last, in case !EN)
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bx lr
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ENDPROC(__vfp_restore_state)
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.popsection