From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoffer Dall Subject: Re: [PATCH v6 11/13] KVM: arm64: Handle RAS SErrors from EL1 on guest exit Date: Fri, 19 Jan 2018 20:20:55 +0100 Message-ID: <20180119192055.GH21802@cbox> References: <20180115193906.30053-1-james.morse@arm.com> <20180115193906.30053-12-james.morse@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 0238E49DF7 for ; Fri, 19 Jan 2018 14:15:49 -0500 (EST) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8MOYg1Y-4uLL for ; Fri, 19 Jan 2018 14:15:47 -0500 (EST) Received: from mail-wm0-f67.google.com (mail-wm0-f67.google.com [74.125.82.67]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id AE93E49DC0 for ; Fri, 19 Jan 2018 14:15:47 -0500 (EST) Received: by mail-wm0-f67.google.com with SMTP id x4so8597447wmc.0 for ; Fri, 19 Jan 2018 11:20:57 -0800 (PST) Content-Disposition: inline In-Reply-To: <20180115193906.30053-12-james.morse@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: James Morse Cc: Jonathan.Zhang@cavium.com, Marc Zyngier , Catalin Marinas , Will Deacon , Dongjiu Geng , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org List-Id: kvmarm@lists.cs.columbia.edu On Mon, Jan 15, 2018 at 07:39:04PM +0000, James Morse wrote: > We expect to have firmware-first handling of RAS SErrors, with errors > notified via an APEI method. For systems without firmware-first, add > some minimal handling to KVM. > > There are two ways KVM can take an SError due to a guest, either may be a > RAS error: we exit the guest due to an SError routed to EL2 by HCR_EL2.AMO, > or we take an SError from EL2 when we unmask PSTATE.A from __guest_exit. > > For SError that interrupt a guest and are routed to EL2 the existing > behaviour is to inject an impdef SError into the guest. > > Add code to handle RAS SError based on the ESR. For uncontained and > uncategorized errors arm64_is_fatal_ras_serror() will panic(), these > errors compromise the host too. All other error types are contained: > For the fatal errors the vCPU can't make progress, so we inject a virtual > SError. We ignore contained errors where we can make progress as if > we're lucky, we may not hit them again. > > If only some of the CPUs support RAS the guest will see the cpufeature > sanitised version of the id registers, but we may still take RAS SError > on this CPU. Move the SError handling out of handle_exit() into a new > handler that runs before we can be preempted. This allows us to use > this_cpu_has_cap(), via arm64_is_ras_serror(). Would it be possible to optimize this a bit later on by caching this_cpu_has_cap() in vcpu_load() so that we can use a single handle_exit function to process all exits? Thanks, -Christoffer > > Signed-off-by: James Morse > --- > Changes since v4: > * Moved SError handling into handle_exit_early(). This will need to move > earlier, into an SError-masked region once we support kernel-first. > (hence the vauge name) > * Dropped Marc & Christoffer's Reviewed-by due to handle_exit_early(). > > arch/arm/include/asm/kvm_host.h | 3 +++ > arch/arm64/include/asm/kvm_host.h | 2 ++ > arch/arm64/kvm/handle_exit.c | 18 +++++++++++++++++- > virt/kvm/arm/arm.c | 3 +++ > 4 files changed, 25 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > index b86fc4162539..acbf9ec7b396 100644 > --- a/arch/arm/include/asm/kvm_host.h > +++ b/arch/arm/include/asm/kvm_host.h > @@ -238,6 +238,9 @@ int kvm_arm_coproc_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *); > int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run, > int exception_index); > > +static inline void handle_exit_early(struct kvm_vcpu *vcpu, struct kvm_run *run, > + int exception_index) {} > + > static inline void __cpu_init_hyp_mode(phys_addr_t pgd_ptr, > unsigned long hyp_stack_ptr, > unsigned long vector_ptr) > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 84fcb2a896a1..abcfd164e690 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -347,6 +347,8 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot); > > int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run, > int exception_index); > +void handle_exit_early(struct kvm_vcpu *vcpu, struct kvm_run *run, > + int exception_index); > > int kvm_perf_init(void); > int kvm_perf_teardown(void); > diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c > index 304203fa9e33..6a5a5db4292f 100644 > --- a/arch/arm64/kvm/handle_exit.c > +++ b/arch/arm64/kvm/handle_exit.c > @@ -29,12 +29,19 @@ > #include > #include > #include > +#include > > #define CREATE_TRACE_POINTS > #include "trace.h" > > typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *); > > +static void kvm_handle_guest_serror(struct kvm_vcpu *vcpu, u32 esr) > +{ > + if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(NULL, esr)) > + kvm_inject_vabt(vcpu); > +} > + > static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run) > { > int ret; > @@ -252,7 +259,6 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run, > case ARM_EXCEPTION_IRQ: > return 1; > case ARM_EXCEPTION_EL1_SERROR: > - kvm_inject_vabt(vcpu); > /* We may still need to return for single-step */ > if (!(*vcpu_cpsr(vcpu) & DBG_SPSR_SS) > && kvm_arm_handle_step_debug(vcpu, run)) > @@ -275,3 +281,13 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run, > return 0; > } > } > + > +/* For exit types that need handling before we can be preempted */ > +void handle_exit_early(struct kvm_vcpu *vcpu, struct kvm_run *run, > + int exception_index) > +{ > + exception_index = ARM_EXCEPTION_CODE(exception_index); > + > + if (exception_index == ARM_EXCEPTION_EL1_SERROR) > + kvm_handle_guest_serror(vcpu, kvm_vcpu_get_hsr(vcpu)); > +} > diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c > index 38e81631fc91..15bf026eb182 100644 > --- a/virt/kvm/arm/arm.c > +++ b/virt/kvm/arm/arm.c > @@ -763,6 +763,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) > guest_exit(); > trace_kvm_exit(ret, kvm_vcpu_trap_get_class(vcpu), *vcpu_pc(vcpu)); > > + /* Exit types that need handling before we can be preempted */ > + handle_exit_early(vcpu, run, ret); > + > preempt_enable(); > > ret = handle_exit(vcpu, run, ret); > -- > 2.15.1 >