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[31.30.174.132]) by smtp.gmail.com with ESMTPSA id ga12sm1302177ejc.13.2021.05.13.00.08.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 May 2021 00:08:59 -0700 (PDT) Date: Thu, 13 May 2021 09:08:57 +0200 From: Andrew Jones To: Alexandru Elisei Cc: kvm@vger.kernel.org, nikos.nikoleris@arm.com, andre.przywara@arm.com, eric.auger@redhat.com Subject: Re: [PATCH kvm-unit-tests v3 8/8] arm/arm64: psci: Don't assume method is hvc Message-ID: <20210513070857.z22utxgp3vooar7u@gator> References: <20210429164130.405198-1-drjones@redhat.com> <20210429164130.405198-9-drjones@redhat.com> <3dd4b8f6-612d-e0c0-f5b5-d8a380213a1d@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3dd4b8f6-612d-e0c0-f5b5-d8a380213a1d@arm.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, May 12, 2021 at 05:14:24PM +0100, Alexandru Elisei wrote: > Hi Drew, > > On 4/29/21 5:41 PM, Andrew Jones wrote: > > The method can be smc in addition to hvc, and it will be when running > > on bare metal. Additionally, we move the invocations to assembly so > > we don't have to rely on compiler assumptions. We also fix the > > prototype of psci_invoke. It should return long, not int, and > > function_id should be an unsigned int, not an unsigned long. > > Sorry to harp on this again, but to be honest, it's still not clear to me why the > psci_invoke_{hvc,smc} functions return a long int. > > If we only expect the PSCI functions to return error codes, then the PSCI spec > says these are 32-bit signed integers. If we want to support PSCI functions > returning other values, like PSCI_STAT_{RESIDENCY,COUNT}, then the invoke > functions should return an unsigned value. > > The only case we're supporting is the error return for the SMC calling convention > (which says that error codes are 32/64bit signed integers). psci_invoke_{hvc,smc} should implement the SMC calling convention, since they're just wrapping the smc/hvc call. PSCI calls that build on that, e.g. psci_cpu_on, can define their own return type and then translate the signed long returned by SMC into, e.g. 32-bit signed integers. Indeed that's what psci_cpu_on does. I would write something like that in the commit message or rename psci_invoke to smc_invoke. Thanks, drew > Since the commit > specifically mentions this change, I think some explanation why this width was > chosen would be appropriate. Unless it's painfully obvious and I'm just not seeing > it, which is a possibility. > > Other than that, the patch looks good. I'll some tests to make sure everything is > in order. > > Thanks, > > Alex > > > > > Signed-off-by: Andrew Jones > > --- > > arm/cstart.S | 22 ++++++++++++++++++++++ > > arm/cstart64.S | 22 ++++++++++++++++++++++ > > arm/selftest.c | 34 +++++++--------------------------- > > lib/arm/asm/psci.h | 10 ++++++++-- > > lib/arm/psci.c | 35 +++++++++++++++++++++++++++-------- > > lib/arm/setup.c | 2 ++ > > 6 files changed, 88 insertions(+), 37 deletions(-) > > > > diff --git a/arm/cstart.S b/arm/cstart.S > > index 446966de350d..2401d92cdadc 100644 > > --- a/arm/cstart.S > > +++ b/arm/cstart.S > > @@ -95,6 +95,28 @@ start: > > > > .text > > > > +/* > > + * psci_invoke_hvc / psci_invoke_smc > > + * > > + * Inputs: > > + * r0 -- function_id > > + * r1 -- arg0 > > + * r2 -- arg1 > > + * r3 -- arg2 > > + * > > + * Outputs: > > + * r0 -- return code > > + */ > > +.globl psci_invoke_hvc > > +psci_invoke_hvc: > > + hvc #0 > > + mov pc, lr > > + > > +.globl psci_invoke_smc > > +psci_invoke_smc: > > + smc #0 > > + mov pc, lr > > + > > enable_vfp: > > /* Enable full access to CP10 and CP11: */ > > mov r0, #(3 << 22 | 3 << 20) > > diff --git a/arm/cstart64.S b/arm/cstart64.S > > index 42ba3a3ca249..e4ab7d06251e 100644 > > --- a/arm/cstart64.S > > +++ b/arm/cstart64.S > > @@ -109,6 +109,28 @@ start: > > > > .text > > > > +/* > > + * psci_invoke_hvc / psci_invoke_smc > > + * > > + * Inputs: > > + * w0 -- function_id > > + * x1 -- arg0 > > + * x2 -- arg1 > > + * x3 -- arg2 > > + * > > + * Outputs: > > + * x0 -- return code > > + */ > > +.globl psci_invoke_hvc > > +psci_invoke_hvc: > > + hvc #0 > > + ret > > + > > +.globl psci_invoke_smc > > +psci_invoke_smc: > > + smc #0 > > + ret > > + > > get_mmu_off: > > adrp x0, auxinfo > > ldr x0, [x0, :lo12:auxinfo + 8] > > diff --git a/arm/selftest.c b/arm/selftest.c > > index 4495b161cdd5..9f459ed3d571 100644 > > --- a/arm/selftest.c > > +++ b/arm/selftest.c > > @@ -400,33 +400,13 @@ static void check_vectors(void *arg __unused) > > exit(report_summary()); > > } > > > > -static bool psci_check(void) > > +static void psci_print(void) > > { > > - const struct fdt_property *method; > > - int node, len, ver; > > - > > - node = fdt_node_offset_by_compatible(dt_fdt(), -1, "arm,psci-0.2"); > > - if (node < 0) { > > - printf("PSCI v0.2 compatibility required\n"); > > - return false; > > - } > > - > > - method = fdt_get_property(dt_fdt(), node, "method", &len); > > - if (method == NULL) { > > - printf("bad psci device tree node\n"); > > - return false; > > - } > > - > > - if (len < 4 || strcmp(method->data, "hvc") != 0) { > > - printf("psci method must be hvc\n"); > > - return false; > > - } > > - > > - ver = psci_invoke(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0); > > - printf("PSCI version %d.%d\n", PSCI_VERSION_MAJOR(ver), > > - PSCI_VERSION_MINOR(ver)); > > - > > - return true; > > + int ver = psci_invoke(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0); > > + report_info("PSCI version: %d.%d", PSCI_VERSION_MAJOR(ver), > > + PSCI_VERSION_MINOR(ver)); > > + report_info("PSCI method: %s", psci_invoke == psci_invoke_hvc ? > > + "hvc" : "smc"); > > } > > > > static void cpu_report(void *data __unused) > > @@ -465,7 +445,7 @@ int main(int argc, char **argv) > > > > } else if (strcmp(argv[1], "smp") == 0) { > > > > - report(psci_check(), "PSCI version"); > > + psci_print(); > > on_cpus(cpu_report, NULL); > > while (!cpumask_full(&ready)) > > cpu_relax(); > > diff --git a/lib/arm/asm/psci.h b/lib/arm/asm/psci.h > > index 7b956bf5987d..f87fca0422cc 100644 > > --- a/lib/arm/asm/psci.h > > +++ b/lib/arm/asm/psci.h > > @@ -3,8 +3,14 @@ > > #include > > #include > > > > -extern int psci_invoke(unsigned long function_id, unsigned long arg0, > > - unsigned long arg1, unsigned long arg2); > > +typedef long (*psci_invoke_fn)(unsigned int function_id, unsigned long arg0, > > + unsigned long arg1, unsigned long arg2); > > +extern psci_invoke_fn psci_invoke; > > +extern long psci_invoke_hvc(unsigned int function_id, unsigned long arg0, > > + unsigned long arg1, unsigned long arg2); > > +extern long psci_invoke_smc(unsigned int function_id, unsigned long arg0, > > + unsigned long arg1, unsigned long arg2); > > +extern void psci_set_conduit(void); > > extern int psci_cpu_on(unsigned long cpuid, unsigned long entry_point); > > extern void psci_system_reset(void); > > extern int cpu_psci_cpu_boot(unsigned int cpu); > > diff --git a/lib/arm/psci.c b/lib/arm/psci.c > > index 936c83948b6a..3053b3041c28 100644 > > --- a/lib/arm/psci.c > > +++ b/lib/arm/psci.c > > @@ -6,22 +6,21 @@ > > * > > * This work is licensed under the terms of the GNU LGPL, version 2. > > */ > > +#include > > #include > > #include > > #include > > #include > > > > -__attribute__((noinline)) > > -int psci_invoke(unsigned long function_id, unsigned long arg0, > > - unsigned long arg1, unsigned long arg2) > > +static long psci_invoke_none(unsigned int function_id, unsigned long arg0, > > + unsigned long arg1, unsigned long arg2) > > { > > - asm volatile( > > - "hvc #0" > > - : "+r" (function_id) > > - : "r" (arg0), "r" (arg1), "r" (arg2)); > > - return function_id; > > + printf("No PSCI method configured! Can't invoke...\n"); > > + return PSCI_RET_NOT_PRESENT; > > } > > > > +psci_invoke_fn psci_invoke = psci_invoke_none; > > + > > int psci_cpu_on(unsigned long cpuid, unsigned long entry_point) > > { > > #ifdef __arm__ > > @@ -56,3 +55,23 @@ void psci_system_off(void) > > int err = psci_invoke(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0); > > printf("CPU%d unable to do system off (error = %d)\n", smp_processor_id(), err); > > } > > + > > +void psci_set_conduit(void) > > +{ > > + const void *fdt = dt_fdt(); > > + const struct fdt_property *method; > > + int node, len; > > + > > + node = fdt_node_offset_by_compatible(fdt, -1, "arm,psci-0.2"); > > + assert_msg(node >= 0, "PSCI v0.2 compatibility required"); > > + > > + method = fdt_get_property(fdt, node, "method", &len); > > + assert(method != NULL && len == 4); > > + > > + if (strcmp(method->data, "hvc") == 0) > > + psci_invoke = psci_invoke_hvc; > > + else if (strcmp(method->data, "smc") == 0) > > + psci_invoke = psci_invoke_smc; > > + else > > + assert_msg(false, "Unknown PSCI conduit: %s", method->data); > > +} > > diff --git a/lib/arm/setup.c b/lib/arm/setup.c > > index 86f054304baf..bcdf0d78c2e2 100644 > > --- a/lib/arm/setup.c > > +++ b/lib/arm/setup.c > > @@ -25,6 +25,7 @@ > > #include > > #include > > #include > > +#include > > > > #include "io.h" > > > > @@ -266,6 +267,7 @@ void setup(const void *fdt, phys_addr_t freemem_start) > > mem_regions_add_assumed(); > > mem_init(PAGE_ALIGN((unsigned long)freemem)); > > > > + psci_set_conduit(); > > cpu_init(); > > > > /* cpu_init must be called before thread_info_init */ >