[v8,14/38] arm64/sme: Implement streaming SVE context switching

Message ID	20220125001114.193425-15-broonie@kernel.org (mailing list archive)
State	New
Headers	show Return-Path: <linux-kselftest-owner@kernel.org> From: Mark Brown <broonie@kernel.org> To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>, Shuah Khan <skhan@linuxfoundation.org>, Shuah Khan <shuah@kernel.org> Cc: Alan Hayward <alan.hayward@arm.com>, Luis Machado <luis.machado@arm.com>, Salil Akerkar <Salil.Akerkar@arm.com>, Basant Kumar Dwivedi <Basant.KumarDwivedi@arm.com>, Szabolcs Nagy <szabolcs.nagy@arm.com>, James Morse <james.morse@arm.com>, Alexandru Elisei <alexandru.elisei@arm.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org, kvmarm@lists.cs.columbia.edu, Mark Brown <broonie@kernel.org> Subject: [PATCH v8 14/38] arm64/sme: Implement streaming SVE context switching Date: Tue, 25 Jan 2022 00:10:50 +0000 Message-Id: <20220125001114.193425-15-broonie@kernel.org> In-Reply-To: <20220125001114.193425-1-broonie@kernel.org> References: <20220125001114.193425-1-broonie@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	arm64/sme: Initial support for the Scalable Matrix Extension \| expand [v8,00/38] arm64/sme: Initial support for the Scalable Matrix Extension [v8,01/38] arm64: cpufeature: Always specify and use a field width for capabilities [v8,02/38] arm64: Add feature detection for fine grained traps [v8,03/38] kselftest/arm64: Remove local ARRAY_SIZE() definitions [v8,04/38] arm64/sme: Provide ABI documentation for SME [v8,05/38] arm64/sme: System register and exception syndrome definitions [v8,06/38] arm64/sme: Manually encode SME instructions [v8,07/38] arm64/sme: Early CPU setup for SME [v8,08/38] arm64/sme: Basic enumeration support [v8,09/38] arm64/sme: Identify supported SME vector lengths at boot [v8,10/38] arm64/sme: Implement sysctl to set the default vector length [v8,11/38] arm64/sme: Implement vector length configuration prctl()s [v8,12/38] arm64/sme: Implement support for TPIDR2 [v8,13/38] arm64/sme: Implement SVCR context switching [v8,14/38] arm64/sme: Implement streaming SVE context switching [v8,15/38] arm64/sme: Implement ZA context switching [v8,16/38] arm64/sme: Implement traps and syscall handling for SME [v8,17/38] arm64/sme: Disable ZA and streaming mode when handling signals [v8,18/38] arm64/sme: Implement streaming SVE signal handling [v8,19/38] arm64/sme: Implement ZA signal handling [v8,20/38] arm64/sme: Implement ptrace support for streaming mode SVE registers [v8,21/38] arm64/sme: Add ptrace support for ZA [v8,22/38] arm64/sme: Disable streaming mode and ZA when flushing CPU state [v8,23/38] arm64/sme: Save and restore streaming mode over EFI runtime calls [v8,24/38] KVM: arm64: Hide SME system registers from guests [v8,25/38] KVM: arm64: Trap SME usage in guest [v8,26/38] KVM: arm64: Handle SME host state when running guests [v8,27/38] arm64/sme: Provide Kconfig for SME [v8,28/38] kselftest/arm64: sme: Add streaming SME support to vlset [v8,29/38] kselftest/arm64: Add tests for TPIDR2 [v8,30/38] kselftest/arm64: Extend vector configuration API tests to cover SME [v8,31/38] kselftest/arm64: sme: Provide streaming mode SVE stress test [v8,32/38] kselftest/arm64: signal: Allow tests to be incompatible with features [v8,33/38] kselftest/arm64: signal: Handle ZA signal context in core code [v8,34/38] kselftest/arm64: Add stress test for SME ZA context switching [v8,35/38] kselftest/arm64: signal: Add SME signal handling tests [v8,36/38] kselftest/arm64: Add streaming SVE to SVE ptrace tests [v8,37/38] kselftest/arm64: Add coverage for the ZA ptrace interface [v8,38/38] kselftest/arm64: Add SME support to syscall ABI test

diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h index d1bae65d3dba..650ec642159c 100644 --- a/arch/arm64/include/asm/fpsimd.h +++ b/arch/arm64/include/asm/fpsimd.h @@ -47,11 +47,21 @@ extern void fpsimd_update_current_state(struct user_fpsimd_state const *state); extern void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *state, void *sve_state, unsigned int sve_vl, - u64 *svcr); + unsigned int sme_vl, u64 *svcr); extern void fpsimd_flush_task_state(struct task_struct *target); extern void fpsimd_save_and_flush_cpu_state(void); +static inline bool thread_sm_enabled(struct thread_struct *thread) +{ + return system_supports_sme() && (thread->svcr & SYS_SVCR_EL0_SM_MASK); +} + +static inline bool thread_za_enabled(struct thread_struct *thread) +{ + return system_supports_sme() && (thread->svcr & SYS_SVCR_EL0_ZA_MASK); +} + /* Maximum VL that SVE/SME VL-agnostic software can transparently support */ #define VL_ARCH_MAX 0x100 @@ -63,7 +73,14 @@ static inline size_t sve_ffr_offset(int vl) static inline void *sve_pffr(struct thread_struct *thread) { - return (char *)thread->sve_state + sve_ffr_offset(thread_get_sve_vl(thread)); + unsigned int vl; + + if (system_supports_sme() && thread_sm_enabled(thread)) + vl = thread_get_sme_vl(thread); + else + vl = thread_get_sve_vl(thread); + + return (char *)thread->sve_state + sve_ffr_offset(vl); } extern void sve_save_state(void *state, u32 *pfpsr, int save_ffr); @@ -72,6 +89,7 @@ extern void sve_load_state(void const *state, u32 const *pfpsr, extern void sve_flush_live(bool flush_ffr, unsigned long vq_minus_1); extern unsigned int sve_get_vl(void); extern void sve_set_vq(unsigned long vq_minus_1); +extern void sme_set_vq(unsigned long vq_minus_1); struct arm64_cpu_capabilities; extern void sve_kernel_enable(const struct arm64_cpu_capabilities *__unused); diff --git a/arch/arm64/include/asm/fpsimdmacros.h b/arch/arm64/include/asm/fpsimdmacros.h index 11c426ddd62c..a50fa1eab730 100644 --- a/arch/arm64/include/asm/fpsimdmacros.h +++ b/arch/arm64/include/asm/fpsimdmacros.h @@ -261,6 +261,17 @@ 921: .endm +/* Update SMCR_EL1.LEN with the new VQ */ +.macro sme_load_vq xvqminus1, xtmp, xtmp2 + mrs_s \xtmp, SYS_SMCR_EL1 + bic \xtmp2, \xtmp, SMCR_ELx_LEN_MASK + orr \xtmp2, \xtmp2, \xvqminus1 + cmp \xtmp2, \xtmp + b.eq 921f + msr_s SYS_SMCR_EL1, \xtmp2 //self-synchronising +921: +.endm + /* Preserve the first 128-bits of Znz and zero the rest. */ .macro _sve_flush_z nz _sve_check_zreg \nz diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 7e08a4d48c24..6e2af9de153c 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -183,6 +183,11 @@ static inline unsigned int thread_get_sve_vl(struct thread_struct *thread) return thread_get_vl(thread, ARM64_VEC_SVE); } +static inline unsigned int thread_get_sme_vl(struct thread_struct *thread) +{ + return thread_get_vl(thread, ARM64_VEC_SME); +} + unsigned int task_get_vl(const struct task_struct *task, enum vec_type type); void task_set_vl(struct task_struct *task, enum vec_type type, unsigned long vl); @@ -196,6 +201,11 @@ static inline unsigned int task_get_sve_vl(const struct task_struct *task) return task_get_vl(task, ARM64_VEC_SVE); } +static inline unsigned int task_get_sme_vl(const struct task_struct *task) +{ + return task_get_vl(task, ARM64_VEC_SME); +} + static inline void task_set_sve_vl(struct task_struct *task, unsigned long vl) { task_set_vl(task, ARM64_VEC_SVE, vl); diff --git a/arch/arm64/kernel/entry-fpsimd.S b/arch/arm64/kernel/entry-fpsimd.S index deee5f01462e..6f88c0f86d50 100644 --- a/arch/arm64/kernel/entry-fpsimd.S +++ b/arch/arm64/kernel/entry-fpsimd.S @@ -94,4 +94,9 @@ SYM_FUNC_START(sme_get_vl) ret SYM_FUNC_END(sme_get_vl) +SYM_FUNC_START(sme_set_vq) + sme_load_vq x0, x1, x2 + ret +SYM_FUNC_END(sme_set_vq) + #endif /* CONFIG_ARM64_SME */ diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index a1918b71d335..12fef62cf07a 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -123,6 +123,7 @@ struct fpsimd_last_state_struct { void *sve_state; u64 *svcr; unsigned int sve_vl; + unsigned int sme_vl; }; static DEFINE_PER_CPU(struct fpsimd_last_state_struct, fpsimd_last_state); @@ -301,17 +302,28 @@ void task_set_vl_onexec(struct task_struct *task, enum vec_type type, task->thread.vl_onexec[type] = vl; } +/* + * TIF_SME controls whether a task can use SME without trapping while + * in userspace, when TIF_SME is set then we must have storage + * alocated in sve_state and za_state to store the contents of both ZA + * and the SVE registers for both streaming and non-streaming modes. + * + * If both SVCR.ZA and SVCR.SM are disabled then at any point we + * may disable TIF_SME and reenable traps. + */ + + /* * TIF_SVE controls whether a task can use SVE without trapping while - * in userspace, and also the way a task's FPSIMD/SVE state is stored - * in thread_struct. + * in userspace, and also (together with TIF_SME) the way a task's + * FPSIMD/SVE state is stored in thread_struct. * * The kernel uses this flag to track whether a user task is actively * using SVE, and therefore whether full SVE register state needs to * be tracked. If not, the cheaper FPSIMD context handling code can * be used instead of the more costly SVE equivalents. * - * * TIF_SVE set: + * * TIF_SVE or SVCR.SM set: * * The task can execute SVE instructions while in userspace without * trapping to the kernel. @@ -319,7 +331,8 @@ void task_set_vl_onexec(struct task_struct *task, enum vec_type type, * When stored, Z0-Z31 (incorporating Vn in bits[127:0] or the * corresponding Zn), P0-P15 and FFR are encoded in in * task->thread.sve_state, formatted appropriately for vector - * length task->thread.sve_vl. + * length task->thread.sve_vl or, if SVCR.SM is set, + * task->thread.sme_vl. * * task->thread.sve_state must point to a valid buffer at least * sve_state_size(task) bytes in size. @@ -357,19 +370,40 @@ void task_set_vl_onexec(struct task_struct *task, enum vec_type type, */ static void task_fpsimd_load(void) { + bool restore_sve_regs = false; + bool restore_ffr; + WARN_ON(!system_supports_fpsimd()); WARN_ON(!have_cpu_fpsimd_context()); - if (IS_ENABLED(CONFIG_ARM64_SME) && test_thread_flag(TIF_SME)) - write_sysreg_s(current->thread.svcr, SYS_SVCR_EL0); - + /* Check if we should restore SVE first */ if (IS_ENABLED(CONFIG_ARM64_SVE) && test_thread_flag(TIF_SVE)) { sve_set_vq(sve_vq_from_vl(task_get_sve_vl(current)) - 1); + restore_sve_regs = true; + restore_ffr = true; + } + + /* Restore SME, override SVE register configuration if needed */ + if (system_supports_sme()) { + unsigned long sme_vl = task_get_sme_vl(current); + + if (test_thread_flag(TIF_SME)) + sme_set_vq(sve_vq_from_vl(sme_vl) - 1); + + write_sysreg_s(current->thread.svcr, SYS_SVCR_EL0); + + if (thread_sm_enabled(&current->thread)) { + restore_sve_regs = true; + restore_ffr = system_supports_fa64(); + } + } + + if (restore_sve_regs) sve_load_state(sve_pffr(&current->thread), - &current->thread.uw.fpsimd_state.fpsr, true); - } else { + &current->thread.uw.fpsimd_state.fpsr, + restore_ffr); + else fpsimd_load_state(&current->thread.uw.fpsimd_state); - } } /* @@ -381,6 +415,9 @@ static void fpsimd_save(void) struct fpsimd_last_state_struct const *last = this_cpu_ptr(&fpsimd_last_state); /* set by fpsimd_bind_task_to_cpu() or fpsimd_bind_state_to_cpu() */ + bool save_sve_regs = false; + bool save_ffr; + unsigned int vl; WARN_ON(!system_supports_fpsimd()); WARN_ON(!have_cpu_fpsimd_context()); @@ -388,15 +425,33 @@ static void fpsimd_save(void) if (test_thread_flag(TIF_FOREIGN_FPSTATE)) return; - if (IS_ENABLED(CONFIG_ARM64_SME) && - test_thread_flag(TIF_SME)) { + if (test_thread_flag(TIF_SVE)) { + save_sve_regs = true; + save_ffr = true; + vl = last->sve_vl; + } + + if (system_supports_sme()) { u64 *svcr = last->svcr; *svcr = read_sysreg_s(SYS_SVCR_EL0); + + if (thread_za_enabled(&current->thread)) { + /* ZA state managment is not implemented yet */ + force_signal_inject(SIGKILL, SI_KERNEL, 0, 0); + return; + } + + /* If we are in streaming mode override regular SVE. */ + if (*svcr & SYS_SVCR_EL0_SM_MASK) { + save_sve_regs = true; + save_ffr = system_supports_fa64(); + vl = last->sme_vl; + } } - if (IS_ENABLED(CONFIG_ARM64_SVE) && - test_thread_flag(TIF_SVE)) { - if (WARN_ON(sve_get_vl() != last->sve_vl)) { + if (IS_ENABLED(CONFIG_ARM64_SVE) && save_sve_regs) { + /* Get the configured VL from RDVL, will account for SM */ + if (WARN_ON(sve_get_vl() != vl)) { /* * Can't save the user regs, so current would * re-enter user with corrupt state. @@ -407,8 +462,8 @@ static void fpsimd_save(void) } sve_save_state((char *)last->sve_state + - sve_ffr_offset(last->sve_vl), - &last->st->fpsr, true); + sve_ffr_offset(vl), + &last->st->fpsr, save_ffr); } else { fpsimd_save_state(last->st); } @@ -613,7 +668,14 @@ static void sve_to_fpsimd(struct task_struct *task) */ static size_t sve_state_size(struct task_struct const *task) { - return SVE_SIG_REGS_SIZE(sve_vq_from_vl(task_get_sve_vl(task))); + unsigned int vl = 0; + + if (system_supports_sve()) + vl = task_get_sve_vl(task); + if (system_supports_sme()) + vl = max(vl, task_get_sme_vl(task)); + + return SVE_SIG_REGS_SIZE(sve_vq_from_vl(vl)); } /* @@ -742,7 +804,8 @@ int vec_set_vector_length(struct task_struct *task, enum vec_type type, } fpsimd_flush_task_state(task); - if (test_and_clear_tsk_thread_flag(task, TIF_SVE)) + if (test_and_clear_tsk_thread_flag(task, TIF_SVE) || + thread_sm_enabled(&task->thread)) sve_to_fpsimd(task); if (system_supports_sme() && type == ARM64_VEC_SME) @@ -1369,6 +1432,9 @@ void fpsimd_flush_thread(void) fpsimd_flush_thread_vl(ARM64_VEC_SVE); } + if (system_supports_sme()) + fpsimd_flush_thread_vl(ARM64_VEC_SME); + put_cpu_fpsimd_context(); } @@ -1412,6 +1478,7 @@ static void fpsimd_bind_task_to_cpu(void) last->st = &current->thread.uw.fpsimd_state; last->sve_state = current->thread.sve_state; last->sve_vl = task_get_sve_vl(current); + last->sme_vl = task_get_sme_vl(current); last->svcr = &current->thread.svcr; current->thread.fpsimd_cpu = smp_processor_id(); @@ -1427,7 +1494,8 @@ static void fpsimd_bind_task_to_cpu(void) } void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st, void *sve_state, - unsigned int sve_vl, u64 *svcr) + unsigned int sve_vl, unsigned int sme_vl, + u64 *svcr) { struct fpsimd_last_state_struct *last = this_cpu_ptr(&fpsimd_last_state); @@ -1439,6 +1507,7 @@ void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st, void *sve_state, last->svcr = svcr; last->sve_state = sve_state; last->sve_vl = sve_vl; + last->sme_vl = sme_vl; } /* diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index 04698c4bcd30..902c598b7ed2 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -109,7 +109,8 @@ void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu) */ fpsimd_bind_state_to_cpu(&vcpu->arch.ctxt.fp_regs, vcpu->arch.sve_state, - vcpu->arch.sve_max_vl); + vcpu->arch.sve_max_vl, + 0); clear_thread_flag(TIF_FOREIGN_FPSTATE); update_thread_flag(TIF_SVE, vcpu_has_sve(vcpu));

[v8,14/38] arm64/sme: Implement streaming SVE context switching

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