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[34.83.12.150]) by smtp.gmail.com with ESMTPSA id b1sm13179440pgf.84.2021.04.26.11.58.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Apr 2021 11:58:16 -0700 (PDT) Date: Mon, 26 Apr 2021 11:58:13 -0700 From: Ricardo Koller To: Andrew Jones Cc: Marc Zyngier , kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, pbonzini@redhat.com, alexandru.elisei@arm.com, eric.auger@redhat.com Subject: Re: [PATCH 1/3] KVM: selftests: Add exception handling support for aarch64 Message-ID: References: <20210423040351.1132218-1-ricarkol@google.com> <20210423040351.1132218-2-ricarkol@google.com> <87sg3hnzrj.wl-maz@kernel.org> <20210423110529.vivemdwnznhblhyf@gator> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210423110529.vivemdwnznhblhyf@gator> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Apr 23, 2021 at 01:05:29PM +0200, Andrew Jones wrote: > On Fri, Apr 23, 2021 at 09:58:24AM +0100, Marc Zyngier wrote: > > Hi Ricardo, > > > > Thanks for starting this. > > Indeed! Thank you for contributing to AArch64 kvm selftests! > > > > +void vm_handle_exception(struct kvm_vm *vm, int vector, int ec, > > > + void (*handler)(struct ex_regs *)); > > > + > > > +#define SPSR_D (1 << 9) > > > +#define SPSR_SS (1 << 21) > > > + > > > +#define write_sysreg(reg, val) \ > > > +({ \ > > > + asm volatile("msr "__stringify(reg)", %0" : : "r"(val)); \ > > > +}) > > Linux does fancy stuff with the Z constraint to allow xzr. We might as > well copy that. > > > > diff --git a/tools/testing/selftests/kvm/lib/aarch64/handlers.S b/tools/testing/selftests/kvm/lib/aarch64/handlers.S > > > new file mode 100644 > > > index 000000000000..c920679b87c0 > > > --- /dev/null > > > +++ b/tools/testing/selftests/kvm/lib/aarch64/handlers.S > > > @@ -0,0 +1,104 @@ > > > +/* SPDX-License-Identifier: GPL-2.0 */ > > > +.macro save_registers, el > > > + stp x28, x29, [sp, #-16]! > > > + stp x26, x27, [sp, #-16]! > > > + stp x24, x25, [sp, #-16]! > > > + stp x22, x23, [sp, #-16]! > > > + stp x20, x21, [sp, #-16]! > > > + stp x18, x19, [sp, #-16]! > > > + stp x16, x17, [sp, #-16]! > > > + stp x14, x15, [sp, #-16]! > > > + stp x12, x13, [sp, #-16]! > > > + stp x10, x11, [sp, #-16]! > > > + stp x8, x9, [sp, #-16]! > > > + stp x6, x7, [sp, #-16]! > > > + stp x4, x5, [sp, #-16]! > > > + stp x2, x3, [sp, #-16]! > > > + stp x0, x1, [sp, #-16]! > > > + > > > + .if \el == 0 > > > + mrs x1, sp_el0 > > > + .else > > > + mov x1, sp > > > + .endif > > > > It there any point in saving SP_EL1, given that you already have > > altered it significantly and will not be restoring it? I don't care > > much, and maybe it is useful as debug information, but a comment would > > certainly make the intent clearer. > > kvm-unit-tests takes some pains to save the original sp. We may be able to > take some inspiration from there for this save and restore. > > > > +void kvm_exit_unexpected_vector(int vector, uint64_t ec) > > > +{ > > > + ucall(UCALL_UNHANDLED, 2, vector, ec); > > > +} > > > + > > > +#define HANDLERS_IDX(_vector, _ec) ((_vector * ESR_EC_NUM) + _ec) > > > > This is definitely odd. Not all the ECs are valid for all vector entry > > points. Actually, ECs only make sense for synchronous exceptions, and > > asynchronous events (IRQ, FIQ, SError) cannot populate ESR_ELx. > > For this, kvm-unit-tests provides a separate API for interrupt handler > installation, which ensures ec is not used. Also, kvm-unit-tests uses > a 2-D array [vector][ec] for the synchronous exceptions. I think we > should be able to use a 2-D array here too, instead of the IDX macro. > > > > +void vm_handle_exception(struct kvm_vm *vm, int vector, int ec, > > > + void (*handler)(struct ex_regs *)) > > > > The name seems to be slightly ill defined. To me "handle exception" is > > the action of handling the exception. Here, you are merely installing > > an exception handler. > > > > I agree. Please rename this for all of kvm selftests to something with > 'install' in the name with the first patch of this series. > > Thanks, > drew > Thank you Andrew and Marc for the reviews. Will send v2 with all the feedback.