On 21/06/2019 10:38, Marc Zyngier wrote: > From: Jintack Lim <jintack.lim@xxxxxxxxxx> > > When supporting nested virtualization a guest hypervisor executing AT > instructions must be trapped and emulated by the host hypervisor, > because untrapped AT instructions operating on S1E1 will use the wrong > translation regieme (the one used to emulate virtual EL2 in EL1 instead > of virtual EL1) and AT instructions operating on S12 will not work from > EL1. > > This patch does several things. > > 1. List and define all AT system instructions to emulate and document > the emulation design. > > 2. Implement AT instruction handling logic in EL2. This will be used to > emulate AT instructions executed in the virtual EL2. > > AT instruction emulation works by loading the proper processor > context, which depends on the trapped instruction and the virtual > HCR_EL2, to the EL1 virtual memory control registers and executing AT > instructions. Note that ctxt->hw_sys_regs is expected to have the > proper processor context before calling the handling > function(__kvm_at_insn) implemented in this patch. > > 4. Emulate AT S1E[01] instructions by issuing the same instructions in > EL2. We set the physical EL1 registers, NV and NV1 bits as described in > the AT instruction emulation overview. > > 5. Emulate AT A12E[01] instructions in two steps: First, do the stage-1 > translation by reusing the existing AT emulation functions. Second, do > the stage-2 translation by walking the guest hypervisor's stage-2 page > table in software. Record the translation result to PAR_EL1. > > 6. Emulate AT S1E2 instructions by issuing the corresponding S1E1 > instructions in EL2. We set the physical EL1 registers and the HCR_EL2 > register as described in the AT instruction emulation overview. > > 7. Forward system instruction traps to the virtual EL2 if the corresponding > virtual AT bit is set in the virtual HCR_EL2. > > [ Much logic above has been reworked by Marc Zyngier ] > > Signed-off-by: Jintack Lim <jintack.lim@xxxxxxxxxx> > Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> > Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxx> > --- > arch/arm64/include/asm/kvm_arm.h | 2 + > arch/arm64/include/asm/kvm_asm.h | 2 + > arch/arm64/include/asm/sysreg.h | 17 +++ > arch/arm64/kvm/hyp/Makefile | 1 + > arch/arm64/kvm/hyp/at.c | 217 +++++++++++++++++++++++++++++++ > arch/arm64/kvm/hyp/switch.c | 13 +- > arch/arm64/kvm/sys_regs.c | 202 +++++++++++++++++++++++++++- > 7 files changed, 450 insertions(+), 4 deletions(-) > create mode 100644 arch/arm64/kvm/hyp/at.c > > diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h > index 1e4dbe0b1c8e..9903f10f6343 100644 > --- a/arch/arm64/include/asm/kvm_arm.h > +++ b/arch/arm64/include/asm/kvm_arm.h > @@ -24,6 +24,7 @@ > > /* Hyp Configuration Register (HCR) bits */ > #define HCR_FWB (UL(1) << 46) > +#define HCR_AT (UL(1) << 44) > #define HCR_NV1 (UL(1) << 43) > #define HCR_NV (UL(1) << 42) > #define HCR_API (UL(1) << 41) > @@ -119,6 +120,7 @@ > #define VTCR_EL2_TG0_16K TCR_TG0_16K > #define VTCR_EL2_TG0_64K TCR_TG0_64K > #define VTCR_EL2_SH0_MASK TCR_SH0_MASK > +#define VTCR_EL2_SH0_SHIFT TCR_SH0_SHIFT > #define VTCR_EL2_SH0_INNER TCR_SH0_INNER > #define VTCR_EL2_ORGN0_MASK TCR_ORGN0_MASK > #define VTCR_EL2_ORGN0_WBWA TCR_ORGN0_WBWA > diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h > index 5e956c2cd9b4..1cfa4d2cf772 100644 > --- a/arch/arm64/include/asm/kvm_asm.h > +++ b/arch/arm64/include/asm/kvm_asm.h > @@ -69,6 +69,8 @@ extern void __kvm_tlb_flush_vmid(struct kvm_s2_mmu *mmu); > extern void __kvm_tlb_flush_local_vmid(struct kvm_vcpu *vcpu); > > extern void __kvm_timer_set_cntvoff(u32 cntvoff_low, u32 cntvoff_high); > +extern void __kvm_at_s1e01(struct kvm_vcpu *vcpu, u32 op, u64 vaddr); > +extern void __kvm_at_s1e2(struct kvm_vcpu *vcpu, u32 op, u64 vaddr); > > extern int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu); > > diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h > index 8b95f2c42c3d..b3a8d21c07b3 100644 > --- a/arch/arm64/include/asm/sysreg.h > +++ b/arch/arm64/include/asm/sysreg.h > @@ -536,6 +536,23 @@ > > #define SYS_SP_EL2 sys_reg(3, 6, 4, 1, 0) > > +/* AT instructions */ > +#define AT_Op0 1 > +#define AT_CRn 7 > + > +#define OP_AT_S1E1R sys_insn(AT_Op0, 0, AT_CRn, 8, 0) > +#define OP_AT_S1E1W sys_insn(AT_Op0, 0, AT_CRn, 8, 1) > +#define OP_AT_S1E0R sys_insn(AT_Op0, 0, AT_CRn, 8, 2) > +#define OP_AT_S1E0W sys_insn(AT_Op0, 0, AT_CRn, 8, 3) > +#define OP_AT_S1E1RP sys_insn(AT_Op0, 0, AT_CRn, 9, 0) > +#define OP_AT_S1E1WP sys_insn(AT_Op0, 0, AT_CRn, 9, 1) > +#define OP_AT_S1E2R sys_insn(AT_Op0, 4, AT_CRn, 8, 0) > +#define OP_AT_S1E2W sys_insn(AT_Op0, 4, AT_CRn, 8, 1) > +#define OP_AT_S12E1R sys_insn(AT_Op0, 4, AT_CRn, 8, 4) > +#define OP_AT_S12E1W sys_insn(AT_Op0, 4, AT_CRn, 8, 5) > +#define OP_AT_S12E0R sys_insn(AT_Op0, 4, AT_CRn, 8, 6) > +#define OP_AT_S12E0W sys_insn(AT_Op0, 4, AT_CRn, 8, 7) > + > /* Common SCTLR_ELx flags. */ > #define SCTLR_ELx_DSSBS (_BITUL(44)) > #define SCTLR_ELx_ENIA (_BITUL(31)) > diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile > index ea710f674cb6..f7af51647079 100644 > --- a/arch/arm64/kvm/hyp/Makefile > +++ b/arch/arm64/kvm/hyp/Makefile > @@ -19,6 +19,7 @@ obj-$(CONFIG_KVM_ARM_HOST) += entry.o > obj-$(CONFIG_KVM_ARM_HOST) += switch.o > obj-$(CONFIG_KVM_ARM_HOST) += fpsimd.o > obj-$(CONFIG_KVM_ARM_HOST) += tlb.o > +obj-$(CONFIG_KVM_ARM_HOST) += at.o > obj-$(CONFIG_KVM_ARM_HOST) += hyp-entry.o > > # KVM code is run at a different exception code with a different map, so > diff --git a/arch/arm64/kvm/hyp/at.c b/arch/arm64/kvm/hyp/at.c > new file mode 100644 > index 000000000000..0e938b6f8e43 > --- /dev/null > +++ b/arch/arm64/kvm/hyp/at.c > @@ -0,0 +1,217 @@ > +/* > + * Copyright (C) 2017 - Linaro Ltd > + * Author: Jintack Lim <jintack.lim@xxxxxxxxxx> > + * > + * 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/kvm_hyp.h> > +#include <asm/kvm_mmu.h> > + > +struct mmu_config { > + u64 ttbr0; > + u64 ttbr1; > + u64 tcr; > + u64 sctlr; > + u64 vttbr; > + u64 vtcr; > + u64 hcr; > +}; > + > +static void __mmu_config_save(struct mmu_config *config) > +{ > + config->ttbr0 = read_sysreg_el1(SYS_TTBR0); > + config->ttbr1 = read_sysreg_el1(SYS_TTBR1); > + config->tcr = read_sysreg_el1(SYS_TCR); > + config->sctlr = read_sysreg_el1(SYS_SCTLR); > + config->vttbr = read_sysreg(vttbr_el2); > + config->vtcr = read_sysreg(vtcr_el2); > + config->hcr = read_sysreg(hcr_el2); > +} > + > +static void __mmu_config_restore(struct mmu_config *config) > +{ > + write_sysreg_el1(config->ttbr0, SYS_TTBR0); > + write_sysreg_el1(config->ttbr1, SYS_TTBR1); > + write_sysreg_el1(config->tcr, SYS_TCR); > + write_sysreg_el1(config->sctlr, SYS_SCTLR); > + write_sysreg(config->vttbr, vttbr_el2); > + write_sysreg(config->vtcr, vttbr_el2); Copy-paste with terrible consequences! I guess you want to write this one to vtcr_el2. Actually, things still seem to run with that. It looks like that save/restore might not be completely required. This seems to only get called in the context of handle_exit(). At that point I think we don't need to save the *_el2 registers. vttbr_el2 and vtcr_el2 both get set from the vcpu content in __activate_vm() before jumping to EL1 (or vEL2), and hcr_el2 gets set in the same manner in __activate_traps(). I think the *_el1 regs still need the save restore as we don't hit vcpu_load() before re-running the guest after a successful handle_exit(). So unless we plan to call the "at" emulation code within kvm_vcpu_run_vhe(), it should be safe to drop the hcr/vttbr/vtcr from the mmu_config. > + write_sysreg(config->hcr, hcr_el2); > + > + isb(); > +} > + Cheers, -- Julien Thierry
