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SubjectRe: [PATCH v3 1/2] arm64: kvm: Save/restore MTE registers
On Fri, Sep 25, 2020 at 10:36:06AM +0100, 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@arm.com>
> ---
> arch/arm64/include/asm/kvm_host.h | 4 ++++
> arch/arm64/include/asm/sysreg.h | 3 ++-
> arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 14 ++++++++++++++
> arch/arm64/kvm/sys_regs.c | 14 ++++++++++----
> 4 files changed, 30 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index e52c927aade5..4f4360dd149e 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -126,6 +126,8 @@ 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 */
> @@ -142,6 +144,8 @@ 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) */
> 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/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index 52eefe2f7d95..cd60677551b7 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -563,7 +563,8 @@
> #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/kvm/hyp/include/hyp/sysreg-sr.h b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
> index 7a986030145f..a124ffa49ba3 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
> @@ -18,6 +18,11 @@
> static inline void __sysreg_save_common_state(struct kvm_cpu_context *ctxt)
> {
> ctxt_sys_reg(ctxt, MDSCR_EL1) = read_sysreg(mdscr_el1);
> + if (system_supports_mte()) {
> + ctxt_sys_reg(ctxt, RGSR_EL1) = read_sysreg_s(SYS_RGSR_EL1);
> + ctxt_sys_reg(ctxt, GCR_EL1) = read_sysreg_s(SYS_GCR_EL1);
> + ctxt_sys_reg(ctxt, TFSRE0_EL1) = read_sysreg_s(SYS_TFSRE0_EL1);
> + }
> }
>
> static inline void __sysreg_save_user_state(struct kvm_cpu_context *ctxt)
> @@ -45,6 +50,8 @@ 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_el1);
> 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);
>
> ctxt_sys_reg(ctxt, SP_EL1) = read_sysreg(sp_el1);
> ctxt_sys_reg(ctxt, ELR_EL1) = read_sysreg_el1(SYS_ELR);
> @@ -63,6 +70,11 @@ static inline void __sysreg_save_el2_return_state(struct kvm_cpu_context *ctxt)
> static inline void __sysreg_restore_common_state(struct kvm_cpu_context *ctxt)
> {
> write_sysreg(ctxt_sys_reg(ctxt, MDSCR_EL1), mdscr_el1);
> + if (system_supports_mte()) {
> + write_sysreg_s(ctxt_sys_reg(ctxt, RGSR_EL1), SYS_RGSR_EL1);
> + write_sysreg_s(ctxt_sys_reg(ctxt, GCR_EL1), SYS_GCR_EL1);
> + write_sysreg_s(ctxt_sys_reg(ctxt, TFSRE0_EL1), SYS_TFSRE0_EL1);
> + }
> }
>
> static inline void __sysreg_restore_user_state(struct kvm_cpu_context *ctxt)
> @@ -106,6 +118,8 @@ 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 379f4969d0bd..a655f172b5ad 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -1391,6 +1391,12 @@ static bool access_mte_regs(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
> return false;
> }
>
> +static unsigned int mte_visibility(const struct kvm_vcpu *vcpu,
> + const struct sys_reg_desc *rd)
> +{
> + return REG_HIDDEN_USER | REG_HIDDEN_GUEST;
> +}
> +
> /* sys_reg_desc initialiser for known cpufeature ID registers */
> #define ID_SANITISED(name) { \
> SYS_DESC(SYS_##name), \
> @@ -1557,8 +1563,8 @@ 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), access_mte_regs },
> - { SYS_DESC(SYS_GCR_EL1), access_mte_regs },
> + { SYS_DESC(SYS_RGSR_EL1), access_mte_regs, reset_unknown, RGSR_EL1, .visibility = mte_visibility },
> + { SYS_DESC(SYS_GCR_EL1), access_mte_regs, reset_unknown, GCR_EL1, .visibility = mte_visibility },
>
> { 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 },
> @@ -1584,8 +1590,8 @@ 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), access_mte_regs },
> - { SYS_DESC(SYS_TFSRE0_EL1), access_mte_regs },
> + { SYS_DESC(SYS_TFSR_EL1), access_mte_regs, reset_unknown, TFSR_EL1, .visibility = mte_visibility },
> + { SYS_DESC(SYS_TFSRE0_EL1), access_mte_regs, 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 },
> --
> 2.20.1
>
>

Reviewed-by: Andrew Jones <drjones@redhat.com>

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