Re: [PATCH v9 18/27] firmware: qcom_scm: Register Gunyah platform ops

Srinivas Kandagatla
2023-02-07T11:52:31Z

On 20/01/2023 22:46, 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

So far SCM usage has been as library of functions to talk to Secure
world, now why is this selecting GUNYAH, it should be other way round.

>
> 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 92763dce6477..20a1434087eb 100644
> --- a/drivers/firmware/qcom_scm.c
> +++ b/drivers/firmware/qcom_scm.c
> @@ -17,6 +17,7 @@
> #include <linux/clk.h>
> #include <linux/reset-controller.h>
> #include <linux/arm-smccc.h>
> +#include <linux/gunyah_rsc_mgr.h>
>
> #include "qcom_scm.h"
>
> @@ -27,6 +28,9 @@ 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;
> @@ -1292,6 +1296,99 @@ 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)
why can't this be an exported function like other scm interfaces?

We do not need a redirection here tbh.

That will also remove the need of gunyah_platform_hooks.c altogether,
and you could call scm functions directly.
Correct me if this is not the case.

> +{
> + 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;
> + 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);
> + }
> + 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;
> + 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++) {
> + 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, &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;
> @@ -1414,6 +1511,9 @@ static int qcom_scm_probe(struct platform_device *pdev)
> if (download_mode)
> qcom_scm_set_download_mode(true);
>
> + if (gh_rm_register_platform_ops(&qcom_scm_gh_rm_platform_ops))
> + dev_warn(__scm->dev, "Gunyah RM platform ops were already registered\n");
> +
> return 0;
> }
>