On 28.08.25 19:40, Oleksii Moisieiev wrote:
Hello Oleksii
the patch lgtm, just some comments
From: Grygorii Strashko <grygorii_stras...@epam.com>
The commit 3e322bef8bc0 ("xen/arm: firmware: Add SCMI over SMC calls
handling layer") introduces simple driver which forwards SCMI over SMC
calls from hwdom/dom0 to EL3 firmware (TF-A) with a single SCMI OSPM agent
support. While it is working gracefully for hwdom/dom0 use case it doesn't
cover "thin Dom0 with guest domain, which serves as Driver domain"
use-case. In this case HW need to be enable in Driver domain and dom0 is
performing only control functions.
The EL3 SCMI firmware (TF-A) with a single SCMI OSPM agent support is
pretty generic case for the default vendors SDK and new platforms.
This patch enables passthrough of SCMI SMC single agent interface to the
one guest domain serving as Driver domain.
Configure Dom0 to enable SCMI passthrough:
- dom0: add scmi-smc-passthrough to the Xen Command Line
Enabled SCMI passthrough for guest using toolstack in the following way:
- domD: xl.cfg add "arm_sci" option as below
arm_sci = "type=scmi_smc"
- domD: xl.cfg enable access to the "arm,scmi-shmem"
iomem = [
"47ff0,1@22001",
]
- domD: add SCMI nodes to the Driver domain partial device tree as in the
below example:
passthrough {
scmi_shm_0: sram@22001000 {
compatible = "arm,scmi-shmem";
reg = <0x0 0x22001000 0x0 0x1000>;
};
firmware {
compatible = "simple-bus";
scmi: scmi {
compatible = "arm,scmi-smc";
shmem = <&scmi_shm_0>;
...
}
}
}
dom0less case configuration:
- add "xen,sci_type" property for required DomU ("xen,domain") node
xen,sci_type="scmi_smc"
- add scmi nodes to the Driver domain partial device tree the same way
as above and enable access to the "arm,scmi-shmem" according to
dom0less documentation. For example:
scmi_shm_0: sram@22001000 {
compatible = "arm,scmi-shmem";
reg = <0x00 0x22001000 0x00 0x1000>;
-> xen,reg = <0x0 0x47ff0000 0x0 0x1000 0x0 0x22001000>;
-> xen,force-assign-without-iommu;
};
The SCMI SMC single agent interface can be enabled for one and only one
domain. In general, the configuration is similar to any other HW
passthrough, except explicitly enabling SCMI with "arm_sci" xl.cfg option.
Note that "arm,scmi-smc" and "arm,scmi-shmem" nodes will be removed from
dom0/hwdom DT in case of
?
Signed-off-by: Grygorii Strashko <grygorii_stras...@epam.com>
Signed-off-by: Oleksii Moisieiev <oleksii_moisie...@epam.com>
Acked-by: Anthony PERARD <anthony.per...@vates.tech> # tools
---
Changes in v6:
- added generated helpers and types go files
- rename cmdline parameter to scmi-smc-passthrough
- fix goto tag in parse_arm_sci_config
Changes in v5:
- rename dom0_scmi_smc_passthrough to scmi_smc_passthrough
Changes in v4:
- xl.cfg doc
- fix comments from Stefano Stabellini
- fix toolstack code as sugested by Anthony PERARD
- use MATCH_OPTION()
- move arm_sci struct and cfg params in "arch_arm"
- add SCMI passthrough for dom0less case
docs/man/xl.cfg.5.pod.in | 34 ++++++++
docs/misc/arm/device-tree/booting.txt | 15 ++++
docs/misc/xen-command-line.pandoc | 9 +++
tools/golang/xenlight/helpers.gen.go | 41 ++++++++++
tools/golang/xenlight/types.gen.go | 12 +++
tools/include/libxl.h | 5 ++
tools/libs/light/libxl_arm.c | 14 ++++
tools/libs/light/libxl_types.idl | 10 +++
tools/xl/xl_parse.c | 36 +++++++++
xen/arch/arm/dom0less-build.c | 34 +++++++-
xen/arch/arm/firmware/Kconfig | 4 +-
xen/arch/arm/firmware/scmi-smc.c | 112 +++++++++++++++++++++++++-
12 files changed, 321 insertions(+), 5 deletions(-)
[snip]
diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
index 0094cf9e40..7422f4be30 100644
--- a/xen/arch/arm/dom0less-build.c
+++ b/xen/arch/arm/dom0less-build.c
@@ -279,6 +279,36 @@ int __init arch_handle_passthrough_prop(struct kernel_info
*kinfo,
return sci_assign_dt_device(kinfo->bd.d, node);
}
+int __init domu_dt_sci_parse(struct dt_device_node *node,
+ struct xen_domctl_createdomain *d_cfg)
+{
+ const char *sci_type = NULL;
NIT: I think "= NULL" can be omitted.
+ int ret;
+
+ d_cfg->arch.arm_sci_type = XEN_DOMCTL_CONFIG_ARM_SCI_NONE;
+
+ if ( !IS_ENABLED(CONFIG_ARM_SCI) ||
+ !dt_property_read_bool(node, "xen,sci_type") )
+ return 0;
+
+ ret = dt_property_read_string(node, "xen,sci_type", &sci_type);
+ if ( ret )
+ return ret;
+
+ if ( !strcmp(sci_type, "none") )
+ d_cfg->arch.arm_sci_type = XEN_DOMCTL_CONFIG_ARM_SCI_NONE;
+ else if ( !strcmp(sci_type, "scmi_smc") )
+ d_cfg->arch.arm_sci_type = XEN_DOMCTL_CONFIG_ARM_SCI_SCMI_SMC;
+ else
+ {
+ printk(XENLOG_ERR "xen,sci_type in not valid (%s) for domain %s\n",
+ sci_type, dt_node_name(node));
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
int __init arch_parse_dom0less_node(struct dt_device_node *node,
struct boot_domain *bd)
{
@@ -288,7 +318,9 @@ int __init arch_parse_dom0less_node(struct dt_device_node
*node,
d_cfg->arch.gic_version = XEN_DOMCTL_CONFIG_GIC_NATIVE;
d_cfg->flags |= XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap;
- d_cfg->arch.arm_sci_type = XEN_DOMCTL_CONFIG_ARM_SCI_NONE;
+
+ if ( domu_dt_sci_parse(node, d_cfg) )
+ panic("Error getting SCI configuration\n");
if ( !dt_property_read_u32(node, "nr_spis", &d_cfg->arch.nr_spis) )
{
diff --git a/xen/arch/arm/firmware/Kconfig b/xen/arch/arm/firmware/Kconfig
index bbf88fbb9a..5c5f0880c4 100644
--- a/xen/arch/arm/firmware/Kconfig
+++ b/xen/arch/arm/firmware/Kconfig
@@ -25,7 +25,9 @@ config SCMI_SMC
doorbell mechanism and Shared Memory for transport ("arm,scmi-smc"
compatible only). The value of "arm,smc-id" DT property from SCMI
firmware node is used to trap and forward corresponding SCMI SMCs
- to firmware running at EL3, for calls coming from the hardware domain.
+ to firmware running at EL3, for calls coming from the hardware domain
or
+ driver domain.
+ Use with EL3 firmware which supports only single SCMI OSPM agent.
endchoice
diff --git a/xen/arch/arm/firmware/scmi-smc.c b/xen/arch/arm/firmware/scmi-smc.c
index 13d1137592..edc54b11b6 100644
--- a/xen/arch/arm/firmware/scmi-smc.c
+++ b/xen/arch/arm/firmware/scmi-smc.c
@@ -14,6 +14,8 @@
#include <xen/device_tree.h>
#include <xen/errno.h>
#include <xen/init.h>
+#include <xen/iocap.h>
+#include <xen/param.h>
#include <xen/sched.h>
#include <xen/types.h>
@@ -22,7 +24,11 @@
#define SCMI_SMC_ID_PROP "arm,smc-id"
+static bool __ro_after_init opt_scmi_smc_passthrough = false;
NIT: I think "= false" can be omitted.
+boolean_param("scmi-smc-passthrough", opt_scmi_smc_passthrough);
+
static uint32_t __ro_after_init scmi_smc_id;
+static struct domain __read_mostly *scmi_dom;
/*
* Check if provided SMC Function Identifier matches the one known by the SCMI
@@ -50,7 +56,7 @@ static bool scmi_handle_smc(struct cpu_user_regs *regs)
return false;
/* Only the hardware domain should use SCMI calls */
- if ( !is_hardware_domain(current->domain) )
+ if ( scmi_dom != current->domain )
{
gdprintk(XENLOG_WARNING, "SCMI: Unprivileged access attempt\n");
return false;
@@ -75,12 +81,45 @@ static bool scmi_handle_smc(struct cpu_user_regs *regs)
return true;
}
+static int
+scmi_smc_domain_sanitise_config(struct xen_domctl_createdomain *config)
+{
+ if ( config->arch.arm_sci_type != XEN_DOMCTL_CONFIG_ARM_SCI_NONE &&
+ config->arch.arm_sci_type != XEN_DOMCTL_CONFIG_ARM_SCI_SCMI_SMC )
+ return -EINVAL;
+
+ return 0;
+}
+
static int scmi_smc_domain_init(struct domain *d,
struct xen_domctl_createdomain *config)
{
- if ( !is_hardware_domain(d) )
+ /*
+ * scmi_passthrough is not enabled:
+ * - proceed only for hw_domain
+ * - fail if guest domain has SCMI enabled.
+ */
+ if ( !opt_scmi_smc_passthrough && !is_hardware_domain(d) )
+ {
+ if ( config->arch.arm_sci_type == XEN_DOMCTL_CONFIG_ARM_SCI_SCMI_SMC )
+ return -EINVAL;
+ else
+ return 0;
+ }
+ /*
+ * scmi_passthrough is enabled:
+ * - ignore hw_domain
+ * - proceed only for domain with SCMI enabled.
+ */
+ if ( opt_scmi_smc_passthrough &&
+ (config->arch.arm_sci_type == XEN_DOMCTL_CONFIG_ARM_SCI_NONE ||
+ is_hardware_domain(d)) )
return 0;
+ if ( scmi_dom )
+ return -EEXIST;
+
+ scmi_dom = d;
d->arch.sci_enabled = true;
printk(XENLOG_DEBUG "SCMI: %pd init\n", d);
return 0;
@@ -88,12 +127,77 @@ static int scmi_smc_domain_init(struct domain *d,
static void scmi_smc_domain_destroy(struct domain *d)
{
- if ( !is_hardware_domain(d) )
+ if ( scmi_dom && scmi_dom != d )
return;
+ scmi_dom = NULL;
+ d->arch.sci_enabled = false;
printk(XENLOG_DEBUG "SCMI: %pd destroy\n", d);
}
+/*
+ * Handle Dom0 SCMI SMC specific DT nodes
+ *
+ * if scmi_smc_passthrough=false:
+ * - Copy SCMI nodes into Dom0 device tree.
+ * if scmi_smc_passthrough=true:
+ * - skip SCMI nodes from Dom0 DT
+ * - give dom0 control access to SCMI shmem MMIO, so SCMI can be passed
+ * through to guest.
+ */
+static bool scmi_smc_dt_handle_node(struct domain *d,
+ struct dt_device_node *node)
+{
+ static const struct dt_device_match shmem_matches[] __initconst = {
+ DT_MATCH_COMPATIBLE("arm,scmi-shmem"),
+ { /* sentinel */ },
+ };
+ static const struct dt_device_match scmi_matches[] __initconst = {
+ DT_MATCH_PATH("/firmware/scmi"),
+ { /* sentinel */ },
+ };
+
+ /* skip scmi shmem node for dom0 if scmi not enabled */
+ if ( dt_match_node(shmem_matches, node) && !sci_domain_is_enabled(d) )
+ {
+ dt_dprintk("Skip scmi shmem node\n");
+ return true;
+ }
+
+ /*
+ * skip scmi node for dom0 if scmi not enabled, but give dom0 control
+ * access to SCMI shmem
+ */
+ if ( dt_match_node(scmi_matches, node) && !sci_domain_is_enabled(d) )
+ {
+ struct dt_device_node *shmem_node;
+ const __be32 *prop;
+ u64 paddr, size;
NIT: uint64_t please for the new code
+ int ret;
+
+ /* give dom0 control access to SCMI shmem */
+ prop = dt_get_property(node, "shmem", NULL);
+ if ( !prop )
+ return true;
+
+ shmem_node = dt_find_node_by_phandle(be32_to_cpu(*prop));
+ if ( !shmem_node )
+ return true;
+
+ ret = dt_device_get_address(shmem_node, 0, &paddr, &size);
+ if ( ret )
+ return true;
+
+ ret = iomem_permit_access(d, paddr_to_pfn(paddr),
+ paddr_to_pfn(paddr + size - 1));
Shouldn't we at least warn if the access to SCMI shmem is not permitted
for Dom0? Or this is not going to be an issue at all?
+
+ dt_dprintk("Skip scmi node\n");
+ return true;
+ }
+
+ return false;
+}
+
static int __init scmi_check_smccc_ver(void)
{
if ( smccc_ver < ARM_SMCCC_VERSION_1_1 )
@@ -108,8 +212,10 @@ static int __init scmi_check_smccc_ver(void)
static const struct sci_mediator_ops scmi_smc_ops = {
.handle_call = scmi_handle_smc,
+ .domain_sanitise_config = scmi_smc_domain_sanitise_config,
.domain_init = scmi_smc_domain_init,
.domain_destroy = scmi_smc_domain_destroy,
+ .dom0_dt_handle_node = scmi_smc_dt_handle_node,
};
/* Initialize the SCMI layer based on SMCs and Device-tree */
