From patchwork Tue Jun 22 10:56:59 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicholas Piggin X-Patchwork-Id: 1495535 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=kvm-ppc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=YbzqIKRm; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4G8NfZ0Lz1z9sjD for ; Tue, 22 Jun 2021 20:58:13 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230016AbhFVLA2 (ORCPT ); Tue, 22 Jun 2021 07:00:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52788 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229922AbhFVLA1 (ORCPT ); Tue, 22 Jun 2021 07:00:27 -0400 Received: from mail-pg1-x534.google.com (mail-pg1-x534.google.com [IPv6:2607:f8b0:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF900C061574 for ; Tue, 22 Jun 2021 03:58:11 -0700 (PDT) Received: by mail-pg1-x534.google.com with SMTP id m2so16743763pgk.7 for ; Tue, 22 Jun 2021 03:58:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=zKksIi3iobNDKIZiDXIqera5X5YbozPv4TcF08UE7EA=; b=YbzqIKRmxnfL5Zen0t0nqknewQXwLa8Dg3geLkGOwe5xPoBy2yIik/mSNX3tjzqRdq k4jYQsH1FzFIG7jUcNYA8KFzOteCUIWh8sdsXuu1brt3/PUc0kj/tAXOn19VImesZSbK dEADcpbdNPXyT2IhjJNeCUlX7ZdP79N1SuYkznlgJx+i+oRjFB4cZYciNPnLEWw0Cnat hHYsIY6NF9PzCCOawP5NP1BOa/cg9IUnNZMfhwdlcBrJlTYIDjS32kFI6KPyLhGKwwgx aF92fO0NAM6+DwlClFpBcSU635+qT1vxjzWfPnPbJ4z9AYTHinDFxawly7Z+JWqbEJFg EbcA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=zKksIi3iobNDKIZiDXIqera5X5YbozPv4TcF08UE7EA=; b=AzemkR7neC24j4rswnEi1BX1edjWkqnPRua0E1WrTQ2qh1Ya2kofMgq4csR9yP6Y7r Is7DwFK5+htYTYPHW8xBA8vrku9LHbasHu7pnrUKKXQvdy/htoq8k5NjjNu+cIpKmQsH KDcUWZYDX2iNxutp8awrdcCu2N6c7qe5U/nvkny4g1e27PN3vUN2LVQ9+Q3oRwBgvocn pcybWNiNmqFCkLZniQV+IR3Tf6p2BxQIMUwH1eyfySuqQxtvj6aJ+Wdgff8vaJzcLYrj FEQqwBv9fGcYoc7Icve2sUPhETlXLWDjbSBglx4IxWdt+memwsG35GyQjgbWmG5fUSnd fclQ== X-Gm-Message-State: AOAM53261tYHif3+XsDrari+ZHbpB5KsXJ4RlJkWScrD7ZkmIXxcrjDQ ykYUpk946tT4YHMrdV6AOUD+37Zvtps= X-Google-Smtp-Source: ABdhPJwZv/W3X+QQYObSapJUzVOgC4mG0sd7Z/q9rXQGafDQo22cluA9C0VscQZ81/N1E7z8NpipmA== X-Received: by 2002:a65:50c5:: with SMTP id s5mr3227651pgp.138.1624359491426; Tue, 22 Jun 2021 03:58:11 -0700 (PDT) Received: from bobo.ozlabs.ibm.com (60-242-147-73.tpgi.com.au. [60.242.147.73]) by smtp.gmail.com with ESMTPSA id l6sm5623621pgh.34.2021.06.22.03.58.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Jun 2021 03:58:11 -0700 (PDT) From: Nicholas Piggin To: kvm-ppc@vger.kernel.org Cc: Nicholas Piggin , linuxppc-dev@lists.ozlabs.org Subject: [RFC PATCH 06/43] powerpc/time: add API for KVM to re-arm the host timer/decrementer Date: Tue, 22 Jun 2021 20:56:59 +1000 Message-Id: <20210622105736.633352-7-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20210622105736.633352-1-npiggin@gmail.com> References: <20210622105736.633352-1-npiggin@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org Rather than have KVM look up the host timer and fiddle with the irq-work internal details, have the powerpc/time.c code provide a function for KVM to re-arm the Linux timer code when exiting a guest. This is implementation has an improvement over existing code of marking a decrementer interrupt as soft-pending if a timer has expired, rather than setting DEC to a -ve value, which tended to cause host timers to take two interrupts (first hdec to exit the guest, then the immediate dec). Signed-off-by: Nicholas Piggin --- arch/powerpc/include/asm/time.h | 16 +++------- arch/powerpc/kernel/time.c | 52 +++++++++++++++++++++++++++------ arch/powerpc/kvm/book3s_hv.c | 7 ++--- 3 files changed, 49 insertions(+), 26 deletions(-) diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h index 69b6be617772..924b2157882f 100644 --- a/arch/powerpc/include/asm/time.h +++ b/arch/powerpc/include/asm/time.h @@ -99,18 +99,6 @@ extern void div128_by_32(u64 dividend_high, u64 dividend_low, extern void secondary_cpu_time_init(void); extern void __init time_init(void); -#ifdef CONFIG_PPC64 -static inline unsigned long test_irq_work_pending(void) -{ - unsigned long x; - - asm volatile("lbz %0,%1(13)" - : "=r" (x) - : "i" (offsetof(struct paca_struct, irq_work_pending))); - return x; -} -#endif - DECLARE_PER_CPU(u64, decrementers_next_tb); static inline u64 timer_get_next_tb(void) @@ -118,6 +106,10 @@ static inline u64 timer_get_next_tb(void) return __this_cpu_read(decrementers_next_tb); } +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE +void timer_rearm_host_dec(u64 now); +#endif + /* Convert timebase ticks to nanoseconds */ unsigned long long tb_to_ns(unsigned long long tb_ticks); diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 026b3c0b648c..7c9de3498548 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -510,6 +510,16 @@ EXPORT_SYMBOL(profile_pc); * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable... */ #ifdef CONFIG_PPC64 +static inline unsigned long test_irq_work_pending(void) +{ + unsigned long x; + + asm volatile("lbz %0,%1(13)" + : "=r" (x) + : "i" (offsetof(struct paca_struct, irq_work_pending))); + return x; +} + static inline void set_irq_work_pending_flag(void) { asm volatile("stb %0,%1(13)" : : @@ -553,13 +563,44 @@ void arch_irq_work_raise(void) preempt_enable(); } +static void set_dec_or_work(u64 val) +{ + set_dec(val); + /* We may have raced with new irq work */ + if (unlikely(test_irq_work_pending())) + set_dec(1); +} + #else /* CONFIG_IRQ_WORK */ #define test_irq_work_pending() 0 #define clear_irq_work_pending() +static void set_dec_or_work(u64 val) +{ + set_dec(val); +} #endif /* CONFIG_IRQ_WORK */ +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE +void timer_rearm_host_dec(u64 now) +{ + u64 *next_tb = this_cpu_ptr(&decrementers_next_tb); + + WARN_ON_ONCE(!arch_irqs_disabled()); + WARN_ON_ONCE(mfmsr() & MSR_EE); + + if (now >= *next_tb) { + local_paca->irq_happened |= PACA_IRQ_DEC; + } else { + now = *next_tb - now; + if (now <= decrementer_max) + set_dec_or_work(now); + } +} +EXPORT_SYMBOL_GPL(timer_rearm_host_dec); +#endif + /* * timer_interrupt - gets called when the decrementer overflows, * with interrupts disabled. @@ -620,10 +661,7 @@ DEFINE_INTERRUPT_HANDLER_ASYNC(timer_interrupt) } else { now = *next_tb - now; if (now <= decrementer_max) - set_dec(now); - /* We may have raced with new irq work */ - if (test_irq_work_pending()) - set_dec(1); + set_dec_or_work(now); __this_cpu_inc(irq_stat.timer_irqs_others); } @@ -865,11 +903,7 @@ static int decrementer_set_next_event(unsigned long evt, struct clock_event_device *dev) { __this_cpu_write(decrementers_next_tb, get_tb() + evt); - set_dec(evt); - - /* We may have raced with new irq work */ - if (test_irq_work_pending()) - set_dec(1); + set_dec_or_work(evt); return 0; } diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 5ec534620e07..36e1db48fccf 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3913,11 +3913,8 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, vc->entry_exit_map = 0x101; vc->in_guest = 0; - next_timer = timer_get_next_tb(); - set_dec(next_timer - tb); - /* We may have raced with new irq work */ - if (test_irq_work_pending()) - set_dec(1); + timer_rearm_host_dec(tb); + mtspr(SPRN_SPRG_VDSO_WRITE, local_paca->sprg_vdso); kvmhv_load_host_pmu();