Re: [RESEND PATCH v5 03/12] firmware: qcom: scm: smc: switch to using the SCM allocator

From: Bartosz Golaszewski
Date: Tue Nov 21 2023 - 04:47:45 EST

On Tue, 21 Nov 2023 at 07:38, Prasad Sodagudi <quic_psodagud@xxxxxxxxxxx> wrote:
>
>
> On 11/20/2023 5:21 AM, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
> >
> > We need to allocate, map and pass a buffer to the trustzone if we have
> > more than 4 arguments for a given SCM calls. Let's use the new TrustZone
> > allocator for that memory and shrink the code in process.
> >
> > As this code lives in a different compilation unit than the rest of the
> > SCM code, we need to provide a helper in the form of
> > qcom_scm_get_tzmem_pool() that allows the SMC low-level routines to
> > access the SCM memory pool.
> >
> > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
> > Reviewed-by: Andrew Halaney <ahalaney@xxxxxxxxxx>
> > Tested-by: Andrew Halaney <ahalaney@xxxxxxxxxx> # sc8280xp-lenovo-thinkpad-x13s
> > ---
> > drivers/firmware/qcom/qcom_scm-smc.c | 30 ++++++++--------------------
> > drivers/firmware/qcom/qcom_scm.c | 5 +++++
> > drivers/firmware/qcom/qcom_scm.h | 3 +++
> > 3 files changed, 16 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/firmware/qcom/qcom_scm-smc.c b/drivers/firmware/qcom/qcom_scm-smc.c
> > index 16cf88acfa8e..dca5f3f1883b 100644
> > --- a/drivers/firmware/qcom/qcom_scm-smc.c
> > +++ b/drivers/firmware/qcom/qcom_scm-smc.c
> > @@ -2,6 +2,7 @@
> > /* Copyright (c) 2015,2019 The Linux Foundation. All rights reserved.
> > */
> >
> > +#include <linux/cleanup.h>
> > #include <linux/io.h>
> > #include <linux/errno.h>
> > #include <linux/delay.h>
> > @@ -9,6 +10,7 @@
> > #include <linux/slab.h>
> > #include <linux/types.h>
> > #include <linux/firmware/qcom/qcom_scm.h>
> > +#include <linux/firmware/qcom/qcom_tzmem.h>
> > #include <linux/arm-smccc.h>
> > #include <linux/dma-mapping.h>
> >
> > @@ -150,11 +152,10 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
> > enum qcom_scm_convention qcom_convention,
> > struct qcom_scm_res *res, bool atomic)
> > {
> > + struct qcom_tzmem_pool *mempool = qcom_scm_get_tzmem_pool();
> > int arglen = desc->arginfo & 0xf;
> > int i, ret;
> > - dma_addr_t args_phys = 0;
> > - void *args_virt = NULL;
> > - size_t alloc_len;
> > + void *args_virt __free(qcom_tzmem) = NULL;
> > gfp_t flag = atomic ? GFP_ATOMIC : GFP_KERNEL;
> > u32 smccc_call_type = atomic ? ARM_SMCCC_FAST_CALL : ARM_SMCCC_STD_CALL;
> > u32 qcom_smccc_convention = (qcom_convention == SMC_CONVENTION_ARM_32) ?
> > @@ -172,9 +173,9 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
> > smc.args[i + SCM_SMC_FIRST_REG_IDX] = desc->args[i];
> >
> > if (unlikely(arglen > SCM_SMC_N_REG_ARGS)) {
> > - alloc_len = SCM_SMC_N_EXT_ARGS * sizeof(u64);
> > - args_virt = kzalloc(PAGE_ALIGN(alloc_len), flag);
> > -
> > + args_virt = qcom_tzmem_alloc(mempool,
> > + SCM_SMC_N_EXT_ARGS * sizeof(u64),
> > + flag);
>
> I remember seeing page alignment for this memory allocation in
> downstream code too.
>
> I think, after moving to qcom_tzmem_alloc page alignment is not
> followed. Is this cross checked with firmware requirements?
>

All SCM call requirements are still respected behind the scenes by the
allocator. Please see the implementations of qcom_tzmem_pool_new() and
qcom_tzmem_alloc().

Bart

> > if (!args_virt)
> > return -ENOMEM;
> >
> > @@ -192,25 +193,10 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
> > SCM_SMC_FIRST_EXT_IDX]);
> > }
> >
> > - args_phys = dma_map_single(dev, args_virt, alloc_len,
> > - DMA_TO_DEVICE);
> > -
> > - if (dma_mapping_error(dev, args_phys)) {
> > - kfree(args_virt);
> > - return -ENOMEM;
> > - }
> > -
> > - smc.args[SCM_SMC_LAST_REG_IDX] = args_phys;
> > + smc.args[SCM_SMC_LAST_REG_IDX] = qcom_tzmem_to_phys(args_virt);
> > }
> >
> > - /* ret error check follows after args_virt cleanup*/
> > ret = __scm_smc_do(dev, &smc, &smc_res, atomic);
> > -
> > - if (args_virt) {
> > - dma_unmap_single(dev, args_phys, alloc_len, DMA_TO_DEVICE);
> > - kfree(args_virt);
> > - }
> > -
> > if (ret)
> > return ret;
> >
> > diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> > index 0d4c028be0c1..71e98b666391 100644
> > --- a/drivers/firmware/qcom/qcom_scm.c
> > +++ b/drivers/firmware/qcom/qcom_scm.c
> > @@ -201,6 +201,11 @@ static void qcom_scm_bw_disable(void)
> > enum qcom_scm_convention qcom_scm_convention = SMC_CONVENTION_UNKNOWN;
> > static DEFINE_SPINLOCK(scm_query_lock);
> >
> > +struct qcom_tzmem_pool *qcom_scm_get_tzmem_pool(void)
> > +{
> > + return __scm->mempool;
> > +}
> > +
> > static enum qcom_scm_convention __get_convention(void)
> > {
> > unsigned long flags;
> > diff --git a/drivers/firmware/qcom/qcom_scm.h b/drivers/firmware/qcom/qcom_scm.h
> > index 4532907e8489..aa7d06939f8e 100644
> > --- a/drivers/firmware/qcom/qcom_scm.h
> > +++ b/drivers/firmware/qcom/qcom_scm.h
> > @@ -5,6 +5,7 @@
> > #define __QCOM_SCM_INT_H
> >
> > struct device;
> > +struct qcom_tzmem_pool;
> >
> > enum qcom_scm_convention {
> > SMC_CONVENTION_UNKNOWN,
> > @@ -78,6 +79,8 @@ int scm_legacy_call_atomic(struct device *dev, const struct qcom_scm_desc *desc,
> > int scm_legacy_call(struct device *dev, const struct qcom_scm_desc *desc,
> > struct qcom_scm_res *res);
> >
> > +struct qcom_tzmem_pool *qcom_scm_get_tzmem_pool(void);
> > +
> > #define QCOM_SCM_SVC_BOOT 0x01
> > #define QCOM_SCM_BOOT_SET_ADDR 0x01
> > #define QCOM_SCM_BOOT_TERMINATE_PC 0x02