Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752232AbbFAJQO (ORCPT ); Mon, 1 Jun 2015 05:16:14 -0400 Received: from foss.arm.com ([217.140.101.70]:33398 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752181AbbFAJQB (ORCPT ); Mon, 1 Jun 2015 05:16:01 -0400 Date: Mon, 1 Jun 2015 10:15:52 +0100 From: Will Deacon To: Alex =?iso-8859-1?Q?Benn=E9e?= Cc: "kvm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.cs.columbia.edu" , "christoffer.dall@linaro.org" , Marc Zyngier , "peter.maydell@linaro.org" , "agraf@suse.de" , "drjones@redhat.com" , "pbonzini@redhat.com" , "zhichao.huang@linaro.org" , "jan.kiszka@siemens.com" , "dahi@linux.vnet.ibm.com" , "r65777@freescale.com" , "bp@suse.de" , Gleb Natapov , Jonathan Corbet , Russell King , Catalin Marinas , Ingo Molnar , Peter Zijlstra , Lorenzo Pieralisi , "open list:DOCUMENTATION" , open list , "open list:ABI/API" Subject: Re: [PATCH v5 10/12] KVM: arm64: guest debug, HW assisted debug support Message-ID: <20150601091552.GA1641@arm.com> References: <1432891828-4816-1-git-send-email-alex.bennee@linaro.org> <1432891828-4816-11-git-send-email-alex.bennee@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1432891828-4816-11-git-send-email-alex.bennee@linaro.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5574 Lines: 139 Hi Alex, On Fri, May 29, 2015 at 10:30:26AM +0100, Alex Benn?e wrote: > This adds support for userspace to control the HW debug registers for > guest debug. In the debug ioctl we copy the IMPDEF defined number of > registers into a new register set called host_debug_state. There is now > a new vcpu parameter called debug_ptr which selects which register set > is to copied into the real registers when world switch occurs. > > I've moved some helper functions into the hw_breakpoint.h header for > re-use. > > As with single step we need to tweak the guest registers to enable the > exceptions so we need to save and restore those bits. > > Two new capabilities have been added to the KVM_EXTENSION ioctl to allow > userspace to query the number of hardware break and watch points > available on the host hardware. > > Signed-off-by: Alex Benn?e [...] > diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt > index 33c8143..ada57df 100644 > --- a/Documentation/virtual/kvm/api.txt > +++ b/Documentation/virtual/kvm/api.txt > @@ -2668,7 +2668,7 @@ The top 16 bits of the control field are architecture specific control > flags which can include the following: > > - KVM_GUESTDBG_USE_SW_BP: using software breakpoints [x86, arm64] > - - KVM_GUESTDBG_USE_HW_BP: using hardware breakpoints [x86, s390] > + - KVM_GUESTDBG_USE_HW_BP: using hardware breakpoints [x86, s390, arm64] > - KVM_GUESTDBG_INJECT_DB: inject DB type exception [x86] > - KVM_GUESTDBG_INJECT_BP: inject BP type exception [x86] > - KVM_GUESTDBG_EXIT_PENDING: trigger an immediate guest exit [s390] > @@ -2683,6 +2683,11 @@ updated to the correct (supplied) values. > The second part of the structure is architecture specific and > typically contains a set of debug registers. > > +For arm64 the number of debug registers is implementation defined and > +can be determined by querying the KVM_CAP_GUEST_DEBUG_HW_BPS and > +KVM_CAP_GUEST_DEBUG_HW_WPS capabilities which return a positive number > +indicating the number of supported registers. > + > When debug events exit the main run loop with the reason > KVM_EXIT_DEBUG with the kvm_debug_exit_arch part of the kvm_run > structure containing architecture specific debug information. > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index 0d17c7b..6df47c1 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -307,6 +307,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) > > #define KVM_GUESTDBG_VALID_MASK (KVM_GUESTDBG_ENABLE | \ > KVM_GUESTDBG_USE_SW_BP | \ > + KVM_GUESTDBG_USE_HW_BP | \ > KVM_GUESTDBG_SINGLESTEP) > > /** > @@ -327,6 +328,12 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, > > if (dbg->control & KVM_GUESTDBG_ENABLE) { > vcpu->guest_debug = dbg->control; > + > + /* Hardware assisted Break and Watch points */ > + if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) { > + vcpu->arch.external_debug_state = dbg->arch; > + } > + > } else { > /* If not enabled clear all flags */ > vcpu->guest_debug = 0; > diff --git a/arch/arm64/include/asm/hw_breakpoint.h b/arch/arm64/include/asm/hw_breakpoint.h > index 52b484b..c450552 100644 > --- a/arch/arm64/include/asm/hw_breakpoint.h > +++ b/arch/arm64/include/asm/hw_breakpoint.h > @@ -130,6 +130,18 @@ static inline void ptrace_hw_copy_thread(struct task_struct *task) > } > #endif > > +/* Determine number of BRP registers available. */ > +static inline int get_num_brps(void) > +{ > + return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1; > +} > + > +/* Determine number of WRP registers available. */ > +static inline int get_num_wrps(void) > +{ > + return ((read_cpuid(ID_AA64DFR0_EL1) >> 20) & 0xf) + 1; > +} I'm fine with moving these into the header file, but we should probably revisit this at some point so that we use a shadow value to indicate the minimum number of registers across the system for e.g. big.LITTLE platforms that don't have uniform debug resources. > extern struct pmu perf_ops_bp; > > #endif /* __KERNEL__ */ > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index e5040b6..498d4f7 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -113,12 +113,13 @@ struct kvm_vcpu_arch { > > /* > * For debugging the guest we need to keep a set of debug > - * registers which can override the guests own debug state > + * registers which can override the guest's own debug state > * while being used. These are set via the KVM_SET_GUEST_DEBUG > * ioctl. > */ > struct kvm_guest_debug_arch *debug_ptr; > struct kvm_guest_debug_arch vcpu_debug_state; > + struct kvm_guest_debug_arch external_debug_state; > > /* Pointer to host CPU context */ > kvm_cpu_context_t *host_cpu_context; > diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h > index 43758e7..95168c2 100644 > --- a/arch/arm64/include/uapi/asm/kvm.h > +++ b/arch/arm64/include/uapi/asm/kvm.h > @@ -116,7 +116,7 @@ struct kvm_guest_debug_arch { > > struct kvm_debug_exit_arch { > __u32 hsr; > - __u64 far; > + __u64 far; /* used for watchpoints */ Why not just add the comment with the field in your earlier patch? Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/