Re: [PATCH v10 16/26] firmware: qcom_scm: Register Gunyah platform ops

[Srinivas Kandagatla <srinivas.kandagatla@linaro.org>]

On 14/02/2023 21:24, Elliot Berman wrote:
> 
> Qualcomm platforms have a firmware entity which performs access control
> to physical pages. Dynamically started Gunyah virtual machines use the
> QCOM_SCM_RM_MANAGED_VMID for access. Linux thus needs to assign access
> to the memory used by guest VMs. Gunyah doesn't do this operation for us
> since it is the current VM (typically VMID_HLOS) delegating the access
> and not Gunyah itself. Use the Gunyah platform ops to achieve this so
> that only Qualcomm platforms attempt to make the needed SCM calls.
> 
> Co-developed-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
> Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> ---
>   drivers/firmware/Kconfig    |   2 +
>   drivers/firmware/qcom_scm.c | 100 ++++++++++++++++++++++++++++++++++++
>   2 files changed, 102 insertions(+)
> 
> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
> index b59e3041fd62..b888068ff6f2 100644
> --- a/drivers/firmware/Kconfig
> +++ b/drivers/firmware/Kconfig
> @@ -214,6 +214,8 @@ config MTK_ADSP_IPC
>   
>   config QCOM_SCM
>   	tristate
> +	select VIRT_DRIVERS
> +	select GUNYAH_PLATFORM_HOOKS

This is really making all the Qualcomm platforms either with Gunyah and 
non-Gunyah hypervisors to enable VIRT_DRIVERS and GUNYAH_PLATFORM_HOOKS 
in there kernel builds, that is not right way to do this.

SCM is used as library so lets keep it that way, I have added some 
comments on platform hooks patch and potential way I see that this can 
be done without making SCM aware of GUNAYAH internals.

--srini
>   
>   config QCOM_SCM_DOWNLOAD_MODE_DEFAULT
>   	bool "Qualcomm download mode enabled by default"
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index 468d4d5ab550..875040982b48 100644
> --- a/drivers/firmware/qcom_scm.c
> +++ b/drivers/firmware/qcom_scm.c
> @@ -20,6 +20,7 @@
>   #include <linux/clk.h>
>   #include <linux/reset-controller.h>
>   #include <linux/arm-smccc.h>
> +#include <linux/gunyah_rsc_mgr.h>
>   
>   #include "qcom_scm.h"
>   
> @@ -30,6 +31,9 @@ module_param(download_mode, bool, 0);
>   #define SCM_HAS_IFACE_CLK	BIT(1)
>   #define SCM_HAS_BUS_CLK		BIT(2)
>   
> +#define QCOM_SCM_RM_MANAGED_VMID	0x3A
> +#define QCOM_SCM_MAX_MANAGED_VMID	0x3F
> +
>   struct qcom_scm {
>   	struct device *dev;
>   	struct clk *core_clk;
> @@ -1297,6 +1301,99 @@ int qcom_scm_lmh_dcvsh(u32 payload_fn, u32 payload_reg, u32 payload_val,
>   }
>   EXPORT_SYMBOL(qcom_scm_lmh_dcvsh);
>   
> +static int qcom_scm_gh_rm_pre_mem_share(struct gh_rm *rm, struct gh_rm_mem_parcel *mem_parcel)
> +{
> +	struct qcom_scm_vmperm *new_perms;
> +	u64 src, src_cpy;
> +	int ret = 0, i, n;
> +	u16 vmid;
> +
> +	new_perms = kcalloc(mem_parcel->n_acl_entries, sizeof(*new_perms), GFP_KERNEL);
> +	if (!new_perms)
> +		return -ENOMEM;
> +
> +	for (n = 0; n < mem_parcel->n_acl_entries; n++) {
> +		vmid = le16_to_cpu(mem_parcel->acl_entries[n].vmid);
> +		if (vmid <= QCOM_SCM_MAX_MANAGED_VMID)
> +			new_perms[n].vmid = vmid;
> +		else
> +			new_perms[n].vmid = QCOM_SCM_RM_MANAGED_VMID;
> +		if (mem_parcel->acl_entries[n].perms & GH_RM_ACL_X)
> +			new_perms[n].perm |= QCOM_SCM_PERM_EXEC;
> +		if (mem_parcel->acl_entries[n].perms & GH_RM_ACL_W)
> +			new_perms[n].perm |= QCOM_SCM_PERM_WRITE;
> +		if (mem_parcel->acl_entries[n].perms & GH_RM_ACL_R)
> +			new_perms[n].perm |= QCOM_SCM_PERM_READ;
> +	}
> +
> +	src = (1ull << QCOM_SCM_VMID_HLOS);
> +
> +	for (i = 0; i < mem_parcel->n_mem_entries; i++) {
> +		src_cpy = src;
> +		ret = qcom_scm_assign_mem(le64_to_cpu(mem_parcel->mem_entries[i].ipa_base),
> +						le64_to_cpu(mem_parcel->mem_entries[i].size),
> +						&src_cpy, new_perms, mem_parcel->n_acl_entries);
> +		if (ret) {
> +			src = 0;
> +			for (n = 0; n < mem_parcel->n_acl_entries; n++) {
> +				vmid = le16_to_cpu(mem_parcel->acl_entries[n].vmid);
> +				if (vmid <= QCOM_SCM_MAX_MANAGED_VMID)
> +					src |= (1ull << vmid);
> +				else
> +					src |= (1ull << QCOM_SCM_RM_MANAGED_VMID);
> +			}
> +
> +			new_perms[0].vmid = QCOM_SCM_VMID_HLOS;
> +
> +			for (i--; i >= 0; i--) {
> +				src_cpy = src;
> +				WARN_ON_ONCE(qcom_scm_assign_mem(
> +						le64_to_cpu(mem_parcel->mem_entries[i].ipa_base),
> +						le64_to_cpu(mem_parcel->mem_entries[i].size),
> +						&src_cpy, new_perms, 1));
> +			}
> +			break;
> +		}
> +	}
> +
> +	kfree(new_perms);
> +	return ret;
> +}
> +
> +static int qcom_scm_gh_rm_post_mem_reclaim(struct gh_rm *rm, struct gh_rm_mem_parcel *mem_parcel)
> +{
> +	struct qcom_scm_vmperm new_perms;
> +	u64 src = 0, src_cpy;
> +	int ret = 0, i, n;
> +	u16 vmid;
> +
> +	new_perms.vmid = QCOM_SCM_VMID_HLOS;
> +	new_perms.perm = QCOM_SCM_PERM_EXEC | QCOM_SCM_PERM_WRITE | QCOM_SCM_PERM_READ;
> +
> +	for (n = 0; n < mem_parcel->n_acl_entries; n++) {
> +		vmid = le16_to_cpu(mem_parcel->acl_entries[n].vmid);
> +		if (vmid <= QCOM_SCM_MAX_MANAGED_VMID)
> +			src |= (1ull << vmid);
> +		else
> +			src |= (1ull << QCOM_SCM_RM_MANAGED_VMID);
> +	}
> +
> +	for (i = 0; i < mem_parcel->n_mem_entries; i++) {
> +		src_cpy = src;
> +		ret = qcom_scm_assign_mem(le64_to_cpu(mem_parcel->mem_entries[i].ipa_base),
> +						le64_to_cpu(mem_parcel->mem_entries[i].size),
> +						&src_cpy, &new_perms, 1);
> +		WARN_ON_ONCE(ret);
> +	}
> +
> +	return ret;
> +}
> +
> +static struct gunyah_rm_platform_ops qcom_scm_gh_rm_platform_ops = {
> +	.pre_mem_share = qcom_scm_gh_rm_pre_mem_share,
> +	.post_mem_reclaim = qcom_scm_gh_rm_post_mem_reclaim,
> +};
> +
>   static int qcom_scm_find_dload_address(struct device *dev, u64 *addr)
>   {
>   	struct device_node *tcsr;
> @@ -1500,6 +1597,9 @@ static int qcom_scm_probe(struct platform_device *pdev)
>   	if (download_mode)
>   		qcom_scm_set_download_mode(true);
>   
> +	if (devm_gh_rm_register_platform_ops(&pdev->dev, &qcom_scm_gh_rm_platform_ops))
> +		dev_warn(__scm->dev, "Gunyah RM platform ops were already registered\n");
> +
>   	return 0;
>   }
>