On 02/02/2021 15:36, Marc Zyngier wrote:
On 2021-01-15 15:28, Steven Price wrote:Define the new system registers that MTE introduces and context switch them. The MTE feature is still hidden from the ID register as it isn't supported in a VM yet. Signed-off-by: Steven Price <steven.price@xxxxxxx> --- arch/arm64/include/asm/kvm_host.h | 4 ++ arch/arm64/include/asm/kvm_mte.h | 74 ++++++++++++++++++++++ arch/arm64/include/asm/sysreg.h | 3 +- arch/arm64/kernel/asm-offsets.c | 3 + arch/arm64/kvm/hyp/entry.S | 7 ++ arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 4 ++ arch/arm64/kvm/sys_regs.c | 14 ++-- 7 files changed, 104 insertions(+), 5 deletions(-) create mode 100644 arch/arm64/include/asm/kvm_mte.h diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 11beda85ee7e..51590a397e4b 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -148,6 +148,8 @@ enum vcpu_sysreg { SCTLR_EL1, /* System Control Register */ ACTLR_EL1, /* Auxiliary Control Register */ CPACR_EL1, /* Coprocessor Access Control */ + RGSR_EL1, /* Random Allocation Tag Seed Register */ + GCR_EL1, /* Tag Control Register */ ZCR_EL1, /* SVE Control */ TTBR0_EL1, /* Translation Table Base Register 0 */ TTBR1_EL1, /* Translation Table Base Register 1 */ @@ -164,6 +166,8 @@ enum vcpu_sysreg { TPIDR_EL1, /* Thread ID, Privileged */ AMAIR_EL1, /* Aux Memory Attribute Indirection Register */ CNTKCTL_EL1, /* Timer Control Register (EL1) */ + TFSRE0_EL1, /* Tag Fault Status Register (EL0) */ + TFSR_EL1, /* Tag Fault Stauts Register (EL1) */s/Stauts/Status/ Is there any reason why the MTE registers aren't grouped together?
I has been under the impression this list is sorted by the encoding of the system registers, although double checking I've screwed up the order of TFSRE0_EL1/TFSR_EL1, and not all the other fields are sorted that way.
I'll move them together in their own section.
PAR_EL1, /* Physical Address Register */ MDSCR_EL1, /* Monitor Debug System Control Register */MDCCINT_EL1, /* Monitor Debug Comms Channel Interrupt Enable Reg */ diff --git a/arch/arm64/include/asm/kvm_mte.h b/arch/arm64/include/asm/kvm_mte.hnew file mode 100644 index 000000000000..62bbfae77f33 --- /dev/null +++ b/arch/arm64/include/asm/kvm_mte.h @@ -0,0 +1,74 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2020 ARM Ltd. + */ +#ifndef __ASM_KVM_MTE_H +#define __ASM_KVM_MTE_H + +#ifdef __ASSEMBLY__ + +#include <asm/sysreg.h> + +#ifdef CONFIG_ARM64_MTE + +.macro mte_switch_to_guest g_ctxt, h_ctxt, reg1 +alternative_if_not ARM64_MTE + b .L__skip_switch\@ +alternative_else_nop_endif + mrs \reg1, hcr_el2 + and \reg1, \reg1, #(HCR_ATA) + cbz \reg1, .L__skip_switch\@ + + mrs_s \reg1, SYS_RGSR_EL1 + str \reg1, [\h_ctxt, #CPU_RGSR_EL1] + mrs_s \reg1, SYS_GCR_EL1 + str \reg1, [\h_ctxt, #CPU_GCR_EL1] + mrs_s \reg1, SYS_TFSRE0_EL1 + str \reg1, [\h_ctxt, #CPU_TFSRE0_EL1] + + ldr \reg1, [\g_ctxt, #CPU_RGSR_EL1] + msr_s SYS_RGSR_EL1, \reg1 + ldr \reg1, [\g_ctxt, #CPU_GCR_EL1] + msr_s SYS_GCR_EL1, \reg1 + ldr \reg1, [\g_ctxt, #CPU_TFSRE0_EL1] + msr_s SYS_TFSRE0_EL1, \reg1 + +.L__skip_switch\@: +.endm + +.macro mte_switch_to_hyp g_ctxt, h_ctxt, reg1 +alternative_if_not ARM64_MTE + b .L__skip_switch\@ +alternative_else_nop_endif + mrs \reg1, hcr_el2 + and \reg1, \reg1, #(HCR_ATA) + cbz \reg1, .L__skip_switch\@ + + mrs_s \reg1, SYS_RGSR_EL1 + str \reg1, [\g_ctxt, #CPU_RGSR_EL1] + mrs_s \reg1, SYS_GCR_EL1 + str \reg1, [\g_ctxt, #CPU_GCR_EL1] + mrs_s \reg1, SYS_TFSRE0_EL1 + str \reg1, [\g_ctxt, #CPU_TFSRE0_EL1]Can't the EL0 state save/restore be moved to the C code?
True, that should be safe. I'm not sure how I missed that.
+ + ldr \reg1, [\h_ctxt, #CPU_RGSR_EL1] + msr_s SYS_RGSR_EL1, \reg1 + ldr \reg1, [\h_ctxt, #CPU_GCR_EL1] + msr_s SYS_GCR_EL1, \reg1 + ldr \reg1, [\h_ctxt, #CPU_TFSRE0_EL1] + msr_s SYS_TFSRE0_EL1, \reg1 + +.L__skip_switch\@: +.endm + +#else /* CONFIG_ARM64_MTE */ + +.macro mte_switch_to_guest g_ctxt, h_ctxt, reg1 +.endm + +.macro mte_switch_to_hyp g_ctxt, h_ctxt, reg1 +.endm + +#endif /* CONFIG_ARM64_MTE */ +#endif /* __ASSEMBLY__ */ +#endif /* __ASM_KVM_MTE_H */diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.hindex 8b5e7e5c3cc8..0a01975d331d 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -574,7 +574,8 @@ #define SCTLR_ELx_M (BIT(0)) #define SCTLR_ELx_FLAGS (SCTLR_ELx_M | SCTLR_ELx_A | SCTLR_ELx_C | \ - SCTLR_ELx_SA | SCTLR_ELx_I | SCTLR_ELx_IESB) + SCTLR_ELx_SA | SCTLR_ELx_I | SCTLR_ELx_IESB | \ + SCTLR_ELx_ITFSB) /* SCTLR_EL2 specific flags. */#define SCTLR_EL2_RES1 ((BIT(4)) | (BIT(5)) | (BIT(11)) | (BIT(16)) | \ diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.cindex f42fd9e33981..801531e1fa5c 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -105,6 +105,9 @@ int main(void) DEFINE(VCPU_WORKAROUND_FLAGS, offsetof(struct kvm_vcpu, arch.workaround_flags)); DEFINE(VCPU_HCR_EL2, offsetof(struct kvm_vcpu, arch.hcr_el2)); DEFINE(CPU_USER_PT_REGS, offsetof(struct kvm_cpu_context, regs));+ DEFINE(CPU_RGSR_EL1, offsetof(struct kvm_cpu_context, sys_regs[RGSR_EL1])); + DEFINE(CPU_GCR_EL1, offsetof(struct kvm_cpu_context, sys_regs[GCR_EL1]));+ DEFINE(CPU_TFSRE0_EL1, offsetof(struct kvm_cpu_context, sys_regs[TFSRE0_EL1])); DEFINE(CPU_APIAKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APIAKEYLO_EL1])); DEFINE(CPU_APIBKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APIBKEYLO_EL1])); DEFINE(CPU_APDAKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APDAKEYLO_EL1])); diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index b0afad7a99c6..c67582c6dd55 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -13,6 +13,7 @@ #include <asm/kvm_arm.h> #include <asm/kvm_asm.h> #include <asm/kvm_mmu.h> +#include <asm/kvm_mte.h> #include <asm/kvm_ptrauth.h> .text @@ -51,6 +52,9 @@ alternative_else_nop_endif add x29, x0, #VCPU_CONTEXT + // mte_switch_to_guest(g_ctxt, h_ctxt, tmp1) + mte_switch_to_guest x29, x1, x2 + // Macro ptrauth_switch_to_guest format: // ptrauth_switch_to_guest(guest cxt, tmp1, tmp2, tmp3)// The below macro to restore guest keys is not implemented in C code@@ -140,6 +144,9 @@ SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL) // when this feature is enabled for kernel code. ptrauth_switch_to_hyp x1, x2, x3, x4, x5 + // mte_switch_to_hyp(g_ctxt, h_ctxt, reg1) + mte_switch_to_hyp x1, x2, x3 + // Restore hyp's sp_el0 restore_sp_el0 x2, x3 diff --git a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h index cce43bfe158f..94d9736f0133 100644 --- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h +++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h @@ -45,6 +45,8 @@ static inline void __sysreg_save_el1_state(struct kvm_cpu_context *ctxt) ctxt_sys_reg(ctxt, CNTKCTL_EL1) = read_sysreg_el1(SYS_CNTKCTL); ctxt_sys_reg(ctxt, PAR_EL1) = read_sysreg_par(); ctxt_sys_reg(ctxt, TPIDR_EL1) = read_sysreg(tpidr_el1); + if (system_supports_mte()) + ctxt_sys_reg(ctxt, TFSR_EL1) = read_sysreg_el1(SYS_TFSR);I already asked for it, and I'm going to ask for it again: Most of the sysreg save/restore is guarded by a per-vcpu check (HCR_EL2.ATA), while this one is unconditionally saved/restore if the host is MTE capable. Why is that so?
Sorry, I thought your concern was for registers that affect the host (as they are obviously more performance critical as they are hit on every guest exit). Although I guess that's incorrect for nVHE which is what all the cool kids want now ;)
The required infrastructure should be available, and if anything is missing, let's add it.
I think I can see a way of accessing the necessary state.
ctxt_sys_reg(ctxt, SP_EL1) = read_sysreg(sp_el1); ctxt_sys_reg(ctxt, ELR_EL1) = read_sysreg_el1(SYS_ELR); @@ -106,6 +108,8 @@ static inline void __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt) write_sysreg_el1(ctxt_sys_reg(ctxt, CNTKCTL_EL1), SYS_CNTKCTL); write_sysreg(ctxt_sys_reg(ctxt, PAR_EL1), par_el1); write_sysreg(ctxt_sys_reg(ctxt, TPIDR_EL1), tpidr_el1); + if (system_supports_mte()) + write_sysreg_el1(ctxt_sys_reg(ctxt, TFSR_EL1), SYS_TFSR); if (!has_vhe() && cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT) && diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 3313dedfa505..88d4f360949e 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1281,6 +1281,12 @@ static bool access_ccsidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p, return true; } +static unsigned int mte_visibility(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd) +{ + return REG_HIDDEN; +} + /* sys_reg_desc initialiser for known cpufeature ID registers */ #define ID_SANITISED(name) { \ SYS_DESC(SYS_##name), \@@ -1449,8 +1455,8 @@ static const struct sys_reg_desc sys_reg_descs[] = {{ SYS_DESC(SYS_ACTLR_EL1), access_actlr, reset_actlr, ACTLR_EL1 }, { SYS_DESC(SYS_CPACR_EL1), NULL, reset_val, CPACR_EL1, 0 }, - { SYS_DESC(SYS_RGSR_EL1), undef_access }, - { SYS_DESC(SYS_GCR_EL1), undef_access }, + { SYS_DESC(SYS_RGSR_EL1), undef_access, reset_unknown, RGSR_EL1, .visibility = mte_visibility }, + { SYS_DESC(SYS_GCR_EL1), undef_access, reset_unknown, GCR_EL1, .visibility = mte_visibility },Please don't mix implicit and designated assignments, as it is pretty confusing.
Sorry - I was copying the style elsewhere in this list (e.g. just below). I guess it might actually be better to create a new macro for MTE similar to AMU / PTRAUTH - it should remove some of the boilerplate.
Thanks, Steve
{ SYS_DESC(SYS_ZCR_EL1), NULL, reset_val, ZCR_EL1, 0, .visibility = sve_visibility },{ SYS_DESC(SYS_TTBR0_EL1), access_vm_reg, reset_unknown, TTBR0_EL1 }, @@ -1476,8 +1482,8 @@ static const struct sys_reg_desc sys_reg_descs[] = {{ SYS_DESC(SYS_ERXMISC0_EL1), trap_raz_wi }, { SYS_DESC(SYS_ERXMISC1_EL1), trap_raz_wi }, - { SYS_DESC(SYS_TFSR_EL1), undef_access }, - { SYS_DESC(SYS_TFSRE0_EL1), undef_access }, + { SYS_DESC(SYS_TFSR_EL1), undef_access, reset_unknown, TFSR_EL1, .visibility = mte_visibility }, + { SYS_DESC(SYS_TFSRE0_EL1), undef_access, reset_unknown, TFSRE0_EL1, .visibility = mte_visibility }, { SYS_DESC(SYS_FAR_EL1), access_vm_reg, reset_unknown, FAR_EL1 }, { SYS_DESC(SYS_PAR_EL1), NULL, reset_unknown, PAR_EL1 },Thanks, M.
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