On 01/12/15 14:47, Christoffer Dall wrote: > On Tue, Dec 01, 2015 at 01:06:31PM +0000, Marc Zyngier wrote: >> On 01/12/15 12:56, Christoffer Dall wrote: >>> On Fri, Nov 27, 2015 at 06:50:02PM +0000, Marc Zyngier wrote: >>>> Implement the debug save restore as a direct translation of >>>> the assembly code version. >>>> >>>> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> >>>> --- >>>> arch/arm64/kvm/hyp/Makefile | 1 + >>>> arch/arm64/kvm/hyp/debug-sr.c | 130 ++++++++++++++++++++++++++++++++++++++++++ >>>> arch/arm64/kvm/hyp/hyp.h | 9 +++ >>>> 3 files changed, 140 insertions(+) >>>> create mode 100644 arch/arm64/kvm/hyp/debug-sr.c >>>> >>>> diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile >>>> index ec94200..ec14cac 100644 >>>> --- a/arch/arm64/kvm/hyp/Makefile >>>> +++ b/arch/arm64/kvm/hyp/Makefile >>>> @@ -6,3 +6,4 @@ obj-$(CONFIG_KVM_ARM_HOST) += vgic-v2-sr.o >>>> obj-$(CONFIG_KVM_ARM_HOST) += vgic-v3-sr.o >>>> obj-$(CONFIG_KVM_ARM_HOST) += timer-sr.o >>>> obj-$(CONFIG_KVM_ARM_HOST) += sysreg-sr.o >>>> +obj-$(CONFIG_KVM_ARM_HOST) += debug-sr.o >>>> diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c >>>> new file mode 100644 >>>> index 0000000..a0b2b99 >>>> --- /dev/null >>>> +++ b/arch/arm64/kvm/hyp/debug-sr.c >>>> @@ -0,0 +1,130 @@ >>>> +/* >>>> + * Copyright (C) 2015 - 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/compiler.h> >>>> +#include <linux/kvm_host.h> >>>> + >>>> +#include <asm/kvm_mmu.h> >>>> + >>>> +#include "hyp.h" >>>> + >>>> +#define read_debug(r,n) read_sysreg(r##n##_el1) >>>> +#define write_debug(v,r,n) write_sysreg(v, r##n##_el1) >>>> + >>>> +#define save_debug(ptr,reg,nr) \ >>>> + switch (nr) { \ >>>> + case 15: ptr[15] = read_debug(reg, 15); \ >>>> + case 14: ptr[14] = read_debug(reg, 14); \ >>>> + case 13: ptr[13] = read_debug(reg, 13); \ >>>> + case 12: ptr[12] = read_debug(reg, 12); \ >>>> + case 11: ptr[11] = read_debug(reg, 11); \ >>>> + case 10: ptr[10] = read_debug(reg, 10); \ >>>> + case 9: ptr[9] = read_debug(reg, 9); \ >>>> + case 8: ptr[8] = read_debug(reg, 8); \ >>>> + case 7: ptr[7] = read_debug(reg, 7); \ >>>> + case 6: ptr[6] = read_debug(reg, 6); \ >>>> + case 5: ptr[5] = read_debug(reg, 5); \ >>>> + case 4: ptr[4] = read_debug(reg, 4); \ >>>> + case 3: ptr[3] = read_debug(reg, 3); \ >>>> + case 2: ptr[2] = read_debug(reg, 2); \ >>>> + case 1: ptr[1] = read_debug(reg, 1); \ >>>> + default: ptr[0] = read_debug(reg, 0); \ >>>> + } >>>> + >>>> +#define restore_debug(ptr,reg,nr) \ >>>> + switch (nr) { \ >>>> + case 15: write_debug(ptr[15], reg, 15); \ >>>> + case 14: write_debug(ptr[14], reg, 14); \ >>>> + case 13: write_debug(ptr[13], reg, 13); \ >>>> + case 12: write_debug(ptr[12], reg, 12); \ >>>> + case 11: write_debug(ptr[11], reg, 11); \ >>>> + case 10: write_debug(ptr[10], reg, 10); \ >>>> + case 9: write_debug(ptr[9], reg, 9); \ >>>> + case 8: write_debug(ptr[8], reg, 8); \ >>>> + case 7: write_debug(ptr[7], reg, 7); \ >>>> + case 6: write_debug(ptr[6], reg, 6); \ >>>> + case 5: write_debug(ptr[5], reg, 5); \ >>>> + case 4: write_debug(ptr[4], reg, 4); \ >>>> + case 3: write_debug(ptr[3], reg, 3); \ >>>> + case 2: write_debug(ptr[2], reg, 2); \ >>>> + case 1: write_debug(ptr[1], reg, 1); \ >>>> + default: write_debug(ptr[0], reg, 0); \ >>>> + } >>>> + >>>> +void __hyp_text __debug_save_state(struct kvm_vcpu *vcpu, >>>> + struct kvm_guest_debug_arch *dbg, >>>> + struct kvm_cpu_context *ctxt) >>>> +{ >>>> + if (vcpu->arch.debug_flags & KVM_ARM64_DEBUG_DIRTY) { >>>> + u64 aa64dfr0 = read_sysreg(id_aa64dfr0_el1); >>>> + int brps, wrps; >>>> + >>>> + brps = (aa64dfr0 >> 12) & 0xf; >>>> + wrps = (aa64dfr0 >> 20) & 0xf; >>>> + >>>> + save_debug(dbg->dbg_bcr, dbgbcr, brps); >>>> + save_debug(dbg->dbg_bvr, dbgbvr, brps); >>>> + save_debug(dbg->dbg_wcr, dbgwcr, wrps); >>>> + save_debug(dbg->dbg_wvr, dbgwvr, wrps); >>>> + >>>> + ctxt->sys_regs[MDCCINT_EL1] = read_sysreg(mdccint_el1); >>>> + } >>>> +} >>>> + >>>> +void __hyp_text __debug_restore_state(struct kvm_vcpu *vcpu, >>>> + struct kvm_guest_debug_arch *dbg, >>>> + struct kvm_cpu_context *ctxt) >>>> +{ >>>> + if (vcpu->arch.debug_flags & KVM_ARM64_DEBUG_DIRTY) { >>>> + u64 aa64dfr0 = read_sysreg(id_aa64dfr0_el1); >>>> + int brps, wrps; >>>> + >>>> + brps = (aa64dfr0 >> 12) & 0xf; >>>> + wrps = (aa64dfr0 >> 20) & 0xf; >>>> + >>>> + restore_debug(dbg->dbg_bcr, dbgbcr, brps); >>>> + restore_debug(dbg->dbg_bvr, dbgbvr, brps); >>>> + restore_debug(dbg->dbg_wcr, dbgwcr, wrps); >>>> + restore_debug(dbg->dbg_wvr, dbgwvr, wrps); >>>> + >>>> + write_sysreg(ctxt->sys_regs[MDCCINT_EL1], mdccint_el1); >>>> + } >>>> +} >>>> + >>>> +void __hyp_text __debug_cond_save_host_state(struct kvm_vcpu *vcpu) >>>> +{ >>>> + if ((vcpu->arch.ctxt.sys_regs[MDSCR_EL1] & DBG_MDSCR_KDE) || >>>> + (vcpu->arch.ctxt.sys_regs[MDSCR_EL1] & DBG_MDSCR_KDE)) >>>> + vcpu->arch.debug_flags |= KVM_ARM64_DEBUG_DIRTY; >>>> + >>>> + __debug_save_state(vcpu, &vcpu->arch.host_debug_state, >>>> + kern_hyp_va(vcpu->arch.host_cpu_context)); >>> >>> doesn't the assmebly code jump across saving this state neither bits are >>> set where this always saves the state? >> >> It doesn't. The save/restore functions are guarded by tests on >> KVM_ARM64_DEBUG_DIRTY, just like we have skip_debug_state on all actions >> involving the save/restore in the assembly version. > > I think the confusing part is that the save function unconditionally > calls __debug_save_state where the restore function only calls it when > the dirty flag is set. Plus I suck at reading assembly apparently. So the way I initially wrote it, I had the same 'if' statement as in the restore function, making them fairly symmetric. But it quickly became obvious that this double-if was a bit pointless. And actually, I wonder if I shouldn't drop it from the restore function, because it only save us a spurious clear of the dirty bit. >>> in any case, I feel some context is lost when this is moved away from >>> assembly and understanding this patch would be easier if the semantics >>> of these two _cond functions were documented. >> >> I can migrate the existing comments if you think that helps. >> > It just wasn't not quite clear to me exactly when > __debug_cond_save_host_state is called for example - is this going to be > called unconditionally on every entry - that's how I understand it now > anyway. On every entry, yes. I'm trying to have the guest_run function as simple as possible, with the various subsystems making their 'own' decisions. Not optimal (you get to branch for nothing), but clearer. At least for me, but I may be the odd duck out here. Any idea to make the flow look clearer? Thanks, M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
