From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754866AbdCGMCA (ORCPT ); Tue, 7 Mar 2017 07:02:00 -0500 Received: from foss.arm.com ([217.140.101.70]:46618 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752039AbdCGMBu (ORCPT ); Tue, 7 Mar 2017 07:01:50 -0500 Message-ID: <58BE9E14.6040208@arm.com> Date: Tue, 07 Mar 2017 11:48:36 +0000 From: James Morse User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.6.0 MIME-Version: 1.0 To: Tyler Baicar CC: christoffer.dall@linaro.org, marc.zyngier@arm.com, pbonzini@redhat.com, rkrcmar@redhat.com, linux@armlinux.org.uk, catalin.marinas@arm.com, will.deacon@arm.com, rjw@rjwysocki.net, lenb@kernel.org, matt@codeblueprint.co.uk, robert.moore@intel.com, lv.zheng@intel.com, nkaje@codeaurora.org, zjzhang@codeaurora.org, mark.rutland@arm.com, akpm@linux-foundation.org, eun.taik.lee@samsung.com, sandeepa.s.prabhu@gmail.com, labbott@redhat.com, shijie.huang@arm.com, rruigrok@codeaurora.org, paul.gortmaker@windriver.com, tn@semihalf.com, fu.wei@linaro.org, rostedt@goodmis.org, bristot@redhat.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-efi@vger.kernel.org, devel@acpica.org, Suzuki.Poulose@arm.com, punit.agrawal@arm.com, astone@redhat.com, harba@codeaurora.org, hanjun.guo@linaro.org, john.garry@huawei.com, shiju.jose@huawei.com, joe@perches.com Subject: Re: [PATCH V12 10/10] arm/arm64: KVM: add guest SEA support References: <1488833103-21082-1-git-send-email-tbaicar@codeaurora.org> <1488833103-21082-11-git-send-email-tbaicar@codeaurora.org> In-Reply-To: <1488833103-21082-11-git-send-email-tbaicar@codeaurora.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Tyler, On 06/03/17 20:45, Tyler Baicar wrote: > Currently external aborts are unsupported by the guest abort > handling. Add handling for SEAs so that the host kernel reports > SEAs which occur in the guest kernel. > diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h > index e22089f..a1a3dff 100644 > --- a/arch/arm/include/asm/kvm_arm.h > +++ b/arch/arm/include/asm/kvm_arm.h > @@ -187,6 +187,16 @@ > #define FSC_FAULT (0x04) > #define FSC_ACCESS (0x08) > #define FSC_PERM (0x0c) > +#define FSC_SEA (0x10) > +#define FSC_SEA_TTW0 (0x14) > +#define FSC_SEA_TTW1 (0x15) > +#define FSC_SEA_TTW2 (0x16) > +#define FSC_SEA_TTW3 (0x17) > +#define FSC_SECC (0x18) > +#define FSC_SECC_TTW0 (0x1c) aarch32 doesn't have either of these 'TW0' values, it's an unused encoding. (However ...) > +#define FSC_SECC_TTW1 (0x1d) > +#define FSC_SECC_TTW2 (0x1e) > +#define FSC_SECC_TTW3 (0x1f) > > /* Hyp Prefetch Fault Address Register (HPFAR/HDFAR) */ > #define HPFAR_MASK (~0xf) > #endif /* __ASM_ARM_SYSTEM_MISC_H */ > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c > index a5265ed..f3608c9 100644 > --- a/arch/arm/kvm/mmu.c > +++ b/arch/arm/kvm/mmu.c > @@ -1444,8 +1463,21 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run) > > /* Check the stage-2 fault is trans. fault or write fault */ > fault_status = kvm_vcpu_trap_get_fault_type(vcpu); > - if (fault_status != FSC_FAULT && fault_status != FSC_PERM && > - fault_status != FSC_ACCESS) { > + > + /* The host kernel will handle the synchronous external abort. There > + * is no need to pass the error into the guest. > + */ > + if (is_abort_synchronous(fault_status)) { > + if(handle_guest_sea((unsigned long)fault_ipa, > + kvm_vcpu_get_hsr(vcpu))) { ... Looking further up in this function: > is_iabt = kvm_vcpu_trap_is_iabt(vcpu); > if (unlikely(!is_iabt && kvm_vcpu_dabt_isextabt(vcpu))) { > kvm_inject_vabt(vcpu); > return 1; > } ... so external data aborts will have already been 'claimed' by kvm and dealt with, and we already have a helper for spotting external aborts. (sorry I didn't spot it earlier). We need to do the handle_guest_sea() before this code. kvm_inject_vabt() makes an SError interrupt pending for the guest. This makes a synchronous error asynchronous as the guest may have SError interrupts masked. I guess this was the best that could be done at the time of (4055710baca8 "arm/arm64: KVM: Inject virtual abort when guest exits on external abort"), but in the light of this firmware-first handling, I'm not sure its the right thing to do. Is it possible for handle_guest_sea() to return whether it actually found any work to do? If there was none I think we should keep this kvm_inject_vabt() as it is the existing behaviour. > + kvm_err("Failed to handle guest SEA, FSC: EC=%#x xFSC=%#lx ESR_EL2=%#lx\n", > + kvm_vcpu_trap_get_class(vcpu), > + (unsigned long)kvm_vcpu_trap_get_fault(vcpu), > + (unsigned long)kvm_vcpu_get_hsr(vcpu)); > + return -EFAULT; > + } > + } else if (fault_status != FSC_FAULT && fault_status != FSC_PERM && > + fault_status != FSC_ACCESS) { > kvm_err("Unsupported FSC: EC=%#x xFSC=%#lx ESR_EL2=%#lx\n", > kvm_vcpu_trap_get_class(vcpu), > (unsigned long)kvm_vcpu_trap_get_fault(vcpu), > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > index b2d57fc..31c5171 100644 > --- a/arch/arm64/mm/fault.c > +++ b/arch/arm64/mm/fault.c > @@ -602,6 +602,24 @@ static const char *fault_name(unsigned int esr) > } > > /* > + * Handle Synchronous External Aborts that occur in a guest kernel. > + */ > +int handle_guest_sea(unsigned long addr, unsigned int esr) > +{ > + /* > + * synchronize_rcu() will wait for nmi_exit(), so no need to > + * rcu_read_lock(). > + */ This comment has a life of its own! Given we don't always call ghes_notify_sea() when we interrupted un-interruptable code its not always true. I think the rcu_read_{,un}lock() should go against the list walk (so it looks like the examples), and ditch the comment! > + if(IS_ENABLED(ACPI_APEI_SEA)) { > + rcu_read_lock(); > + ghes_notify_sea(); > + rcu_read_unlock(); > + } > + > + return 0; > +} > + > +/* > * Dispatch a data abort to the relevant handler. > */ > asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr, > Thanks, James