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[23.128.96.18]) by mx.google.com with ESMTP id n13si3181088ejz.621.2020.09.10.04.34.39; Thu, 10 Sep 2020 04:35:04 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=AA84R5re; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730093AbgIJLYx (ORCPT + 99 others); Thu, 10 Sep 2020 07:24:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727805AbgIJLWg (ORCPT ); Thu, 10 Sep 2020 07:22:36 -0400 Received: from mail-wm1-x341.google.com (mail-wm1-x341.google.com [IPv6:2a00:1450:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5007BC061573 for ; Thu, 10 Sep 2020 04:12:32 -0700 (PDT) Received: by mail-wm1-x341.google.com with SMTP id b79so5373778wmb.4 for ; Thu, 10 Sep 2020 04:12:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=qu8JH/be0rcbIWaaAUE3igFaIOUou49hkjsJpPAPR90=; b=AA84R5regpZTTXFRpYdM+Or0tNH+fSOtcqP2pbugiGih/zhtRpJQ9cnshBMxr/2NFT FkZa3oj1Xp06SJZG9wz5iZrx1xBELEnEKGxVH1OlRfHsL0dtvMMG2hk7s6PB8W+kvyir sX9ek/eZRCmuRjUkFR4kKFs7iBNH565OLxk5AwZyOaq9Qz381ztlKjBTf7fJvXjDMtUv k1mlUwbXnd1c0vx4qoZAdUmGXUdFF9d3I2xnTUUYMiE3r4QfZxZNnlyJVqBmH4suoSEl a1udckqFeJUhnzcnBF+GizdyEJvpBbXbmvGn+XytRvONjxBJByJ66ZY3U9h6PWwIDfMo 1qZg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=qu8JH/be0rcbIWaaAUE3igFaIOUou49hkjsJpPAPR90=; b=I3kWMPm8p7wCW0x2S0Vb3crMRPYmXTyigHjPrU1jXzXsEXkNvCK0sEMT8D4BzP9/AD PeSez9PvUYBJckQKD1sqkI9ZXwxjnsTEuj2ppQwWNgL0hlTGAIJy0u6IMuRwEpvawvaJ Su9IhgDswSSBIewZcHkNJr3nSqjLJYxyIp5drk07Rh3J2wcuN8fVRyYIEWrAk+KSt/Ua Q6ddIw+r4ITPBdRrSOby/8gjWyo9X/6J77n++bptVy6zpz+8q1Q//HABIDLazWOAzEbs sYvSTOvfjx/QJeG6CDG/AUzNYANDt37U3JRCOSJLx1S0RSnHGp3bgg1PHO20Bj89lKHw qVaQ== X-Gm-Message-State: AOAM5324Trv/eAOIGRae7pixvYuuYV6Jf+tZdBsQIVyYeqncFGblKWhb VcReCAVtZ4bL/UiMUM8abdCUIw== X-Received: by 2002:a1c:4886:: with SMTP id v128mr8080271wma.139.1599736350622; Thu, 10 Sep 2020 04:12:30 -0700 (PDT) Received: from google.com ([2a00:79e0:d:109:4a0f:cfff:fe4a:6363]) by smtp.gmail.com with ESMTPSA id t15sm2953444wmj.15.2020.09.10.04.12.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Sep 2020 04:12:30 -0700 (PDT) Date: Thu, 10 Sep 2020 12:12:25 +0100 From: Andrew Scull To: David Brazdil Cc: Marc Zyngier , Catalin Marinas , Will Deacon , Dennis Zhou , Tejun Heo , Christoph Lameter , Arnd Bergmann , James Morse , Julien Thierry , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arch@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v2 03/10] kvm: arm64: Remove __hyp_this_cpu_read Message-ID: <20200910111225.GC93664@google.com> References: <20200903091712.46456-1-dbrazdil@google.com> <20200903091712.46456-4-dbrazdil@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200903091712.46456-4-dbrazdil@google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 03, 2020 at 11:17:05AM +0200, 'David Brazdil' via kernel-team wrote: > this_cpu_ptr is meant for use in kernel proper because it selects between > TPIDR_EL1/2 based on nVHE/VHE. __hyp_this_cpu_ptr was used in hyp to always > select TPIDR_EL2. Unify all users behind this_cpu_ptr and friends by > selecting _EL2 register under __KVM_NVHE_HYPERVISOR__. > > Under CONFIG_DEBUG_PREEMPT, the kernel helpers perform a preemption check > which is omitted by the hyp helpers. Preserve the behavior for nVHE by > overriding the corresponding macros under __KVM_NVHE_HYPERVISOR__. Extend > the checks into VHE hyp code. > > Signed-off-by: David Brazdil > --- > arch/arm64/include/asm/kvm_asm.h | 20 -------------- > arch/arm64/include/asm/percpu.h | 33 +++++++++++++++++++++-- > arch/arm64/kvm/hyp/include/hyp/debug-sr.h | 4 +-- > arch/arm64/kvm/hyp/include/hyp/switch.h | 8 +++--- > arch/arm64/kvm/hyp/nvhe/switch.c | 2 +- > arch/arm64/kvm/hyp/vhe/switch.c | 2 +- > arch/arm64/kvm/hyp/vhe/sysreg-sr.c | 4 +-- > 7 files changed, 41 insertions(+), 32 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h > index 6f98fbd0ac81..9149079f0269 100644 > --- a/arch/arm64/include/asm/kvm_asm.h > +++ b/arch/arm64/include/asm/kvm_asm.h > @@ -149,26 +149,6 @@ extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ]; > addr; \ > }) > > -/* > - * Home-grown __this_cpu_{ptr,read} variants that always work at HYP, > - * provided that sym is really a *symbol* and not a pointer obtained from > - * a data structure. As for SHIFT_PERCPU_PTR(), the creative casting keeps > - * sparse quiet. > - */ > -#define __hyp_this_cpu_ptr(sym) \ > - ({ \ > - void *__ptr; \ > - __verify_pcpu_ptr(&sym); \ > - __ptr = hyp_symbol_addr(sym); \ > - __ptr += read_sysreg(tpidr_el2); \ > - (typeof(sym) __kernel __force *)__ptr; \ > - }) > - > -#define __hyp_this_cpu_read(sym) \ > - ({ \ > - *__hyp_this_cpu_ptr(sym); \ > - }) > - > #define __KVM_EXTABLE(from, to) \ > " .pushsection __kvm_ex_table, \"a\"\n" \ > " .align 3\n" \ > diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h > index 0b6409b89e5e..b4008331475b 100644 > --- a/arch/arm64/include/asm/percpu.h > +++ b/arch/arm64/include/asm/percpu.h > @@ -19,7 +19,21 @@ static inline void set_my_cpu_offset(unsigned long off) > :: "r" (off) : "memory"); > } > > -static inline unsigned long __my_cpu_offset(void) > +static inline unsigned long __hyp_my_cpu_offset(void) > +{ > + unsigned long off; > + > + /* > + * We want to allow caching the value, so avoid using volatile and > + * instead use a fake stack read to hazard against barrier(). > + */ > + asm("mrs %0, tpidr_el2" : "=r" (off) : > + "Q" (*(const unsigned long *)current_stack_pointer)); > + > + return off; > +} > + > +static inline unsigned long __kern_my_cpu_offset(void) > { > unsigned long off; > > @@ -35,7 +49,12 @@ static inline unsigned long __my_cpu_offset(void) > > return off; > } > -#define __my_cpu_offset __my_cpu_offset() > + > +#ifdef __KVM_NVHE_HYPERVISOR__ > +#define __my_cpu_offset __hyp_my_cpu_offset() Is there a benefit to this being used for __KVM_VHE_HYPERVISOR__ too since that is "hyp" too and doesn't need the alternative since it will always pick EL2? > +#else > +#define __my_cpu_offset __kern_my_cpu_offset() > +#endif > > #define PERCPU_RW_OPS(sz) \ > static inline unsigned long __percpu_read_##sz(void *ptr) \ > @@ -227,4 +246,14 @@ PERCPU_RET_OP(add, add, ldadd) > > #include > > +/* Redefine macros for nVHE hyp under DEBUG_PREEMPT to avoid its dependencies. */ > +#if defined(__KVM_NVHE_HYPERVISOR__) && defined(CONFIG_DEBUG_PREEMPT) > +#undef this_cpu_ptr > +#define this_cpu_ptr raw_cpu_ptr > +#undef __this_cpu_read > +#define __this_cpu_read raw_cpu_read > +#undef __this_cpu_write > +#define __this_cpu_write raw_cpu_write > +#endif This is an incomplete cherry-picked list of macros that are redefined to remove the call to __this_cpu_preempt_check that would result in a linker failure since that symbol is not defined for nVHE hyp. I remember there being some dislike of truely defining that symbol with an nVHE hyp implementation but I can't see why. Yes, nVHE hyp is always has preemption disabled so the implementation is just an empty function but why is is preferrable to redefine some of these macros instead? > + > #endif /* __ASM_PERCPU_H */ > diff --git a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h > index 5e28ea6aa097..4ebe9f558f3a 100644 > --- a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h > +++ b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h > @@ -135,7 +135,7 @@ static inline void __debug_switch_to_guest_common(struct kvm_vcpu *vcpu) > if (!(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY)) > return; > > - host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; > + host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt; > guest_ctxt = &vcpu->arch.ctxt; > host_dbg = &vcpu->arch.host_debug_state.regs; > guest_dbg = kern_hyp_va(vcpu->arch.debug_ptr); > @@ -154,7 +154,7 @@ static inline void __debug_switch_to_host_common(struct kvm_vcpu *vcpu) > if (!(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY)) > return; > > - host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; > + host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt; > guest_ctxt = &vcpu->arch.ctxt; > host_dbg = &vcpu->arch.host_debug_state.regs; > guest_dbg = kern_hyp_va(vcpu->arch.debug_ptr); > diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h > index 5b6b8fa00f0a..f150407fa798 100644 > --- a/arch/arm64/kvm/hyp/include/hyp/switch.h > +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h > @@ -386,7 +386,7 @@ static inline bool __hyp_handle_ptrauth(struct kvm_vcpu *vcpu) > !esr_is_ptrauth_trap(kvm_vcpu_get_esr(vcpu))) > return false; > > - ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; > + ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt; > __ptrauth_save_key(ctxt, APIA); > __ptrauth_save_key(ctxt, APIB); > __ptrauth_save_key(ctxt, APDA); > @@ -495,7 +495,7 @@ static inline void __set_guest_arch_workaround_state(struct kvm_vcpu *vcpu) > * guest wants it disabled, so be it... > */ > if (__needs_ssbd_off(vcpu) && > - __hyp_this_cpu_read(arm64_ssbd_callback_required)) > + __this_cpu_read(arm64_ssbd_callback_required)) > arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, 0, NULL); > #endif > } > @@ -507,7 +507,7 @@ static inline void __set_host_arch_workaround_state(struct kvm_vcpu *vcpu) > * If the guest has disabled the workaround, bring it back on. > */ > if (__needs_ssbd_off(vcpu) && > - __hyp_this_cpu_read(arm64_ssbd_callback_required)) > + __this_cpu_read(arm64_ssbd_callback_required)) > arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, 1, NULL); > #endif > } > @@ -521,7 +521,7 @@ static inline void __kvm_unexpected_el2_exception(void) > > entry = hyp_symbol_addr(__start___kvm_ex_table); > end = hyp_symbol_addr(__stop___kvm_ex_table); > - host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; > + host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt; > > while (entry < end) { > addr = (unsigned long)&entry->insn + entry->insn; > diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c > index 0970442d2dbc..cc4f8e790fb3 100644 > --- a/arch/arm64/kvm/hyp/nvhe/switch.c > +++ b/arch/arm64/kvm/hyp/nvhe/switch.c > @@ -175,7 +175,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu) > > vcpu = kern_hyp_va(vcpu); > > - host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; > + host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt; > host_ctxt->__hyp_running_vcpu = vcpu; > guest_ctxt = &vcpu->arch.ctxt; > > diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c > index c1da4f86ccac..575e8054f116 100644 > --- a/arch/arm64/kvm/hyp/vhe/switch.c > +++ b/arch/arm64/kvm/hyp/vhe/switch.c > @@ -108,7 +108,7 @@ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu) > struct kvm_cpu_context *guest_ctxt; > u64 exit_code; > > - host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; > + host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt; > host_ctxt->__hyp_running_vcpu = vcpu; > guest_ctxt = &vcpu->arch.ctxt; > > diff --git a/arch/arm64/kvm/hyp/vhe/sysreg-sr.c b/arch/arm64/kvm/hyp/vhe/sysreg-sr.c > index 996471e4c138..2a0b8c88d74f 100644 > --- a/arch/arm64/kvm/hyp/vhe/sysreg-sr.c > +++ b/arch/arm64/kvm/hyp/vhe/sysreg-sr.c > @@ -66,7 +66,7 @@ void kvm_vcpu_load_sysregs_vhe(struct kvm_vcpu *vcpu) > struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt; > struct kvm_cpu_context *host_ctxt; > > - host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; > + host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt; > __sysreg_save_user_state(host_ctxt); > > /* > @@ -100,7 +100,7 @@ void kvm_vcpu_put_sysregs_vhe(struct kvm_vcpu *vcpu) > struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt; > struct kvm_cpu_context *host_ctxt; > > - host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt; > + host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt; > deactivate_traps_vhe_put(); > > __sysreg_save_el1_state(guest_ctxt); > -- > 2.28.0.402.g5ffc5be6b7-goog > > -- > To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com. >