On 4/17/23 10:44, Nikunj Kela wrote:
This patch add support for passing shmem channel address as parameter
in smc/hvc call. This patch is useful when multiple scmi instances are
using same smc-id and firmware needs to distiguish among the instances.
Typo: distinguish.
It really would have been a lot clearer and made a whole lot more sense
to encode a VM ID/channel number within some of the SMCCC parameters,
possibly as part of the function ID itself.
Signed-off-by: Nikunj Kela <quic_nkela@xxxxxxxxxxx>
---
drivers/firmware/arm_scmi/driver.c | 1 +
drivers/firmware/arm_scmi/smc.c | 25 ++++++++++++++++++++++++-
2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index e7d97b59963b..b5957cc12fee 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -2914,6 +2914,7 @@ static const struct of_device_id scmi_of_match[] = {
#endif
#ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC
{ .compatible = "arm,scmi-smc", .data = &scmi_smc_desc},
+ { .compatible = "arm,scmi-smc-param", .data = &scmi_smc_desc},
#endif
#ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO
{ .compatible = "arm,scmi-virtio", .data = &scmi_virtio_desc},
diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
index 93272e4bbd12..e28387346d33 100644
--- a/drivers/firmware/arm_scmi/smc.c
+++ b/drivers/firmware/arm_scmi/smc.c
@@ -20,6 +20,9 @@
#include "common.h"
+#define lower32(x) ((u32)((x) & 0xffffffff))
+#define upper32(x) ((u32)(((u64)(x) >> 32) & 0xffffffff))
Cannot you use the existing lower_32_bits and upper_32_bits macros from
kernel.h here?
+
/**
* struct scmi_smc - Structure representing a SCMI smc transport
*
@@ -30,6 +33,8 @@
* @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
* Used when operating in atomic mode.
* @func_id: smc/hvc call function id
+ * @is_smc64: smc/hvc calling convention type 64 vs 32
+ * @param: physical address of the shmem channel
*/
struct scmi_smc {
@@ -40,6 +45,8 @@ struct scmi_smc {
#define INFLIGHT_NONE MSG_TOKEN_MAX
atomic_t inflight;
u32 func_id;
+ bool is_smc64;
+ phys_addr_t param;
};
static irqreturn_t smc_msg_done_isr(int irq, void *data)
@@ -137,6 +144,8 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
if (ret < 0)
return ret;
+ if (of_device_is_compatible(dev->of_node, "arm,scmi-smc-param"))
+ scmi_info->param = res.start;
There is not even a check that this is going to be part of the kernel's
view of memory, that seems a bit brittle and possibly a security hole,
too. Your hypervisor presumably needs to have carved out some amount of
memory in order for the messages to be written to/read from, and so
would the VM kernel, so eventually we should have a 'reserved-memory'
entry of some sort, no?
/*
* If there is an interrupt named "a2p", then the service and
* completion of a message is signaled by an interrupt rather than by
@@ -156,6 +165,7 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
}
scmi_info->func_id = func_id;
+ scmi_info->is_smc64 = ARM_SMCCC_IS_64(func_id);
scmi_info->cinfo = cinfo;
smc_channel_lock_init(scmi_info);
cinfo->transport_info = scmi_info;
@@ -188,7 +198,20 @@ static int smc_send_message(struct scmi_chan_info *cinfo,
shmem_tx_prepare(scmi_info->shmem, xfer, cinfo);
- arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
+#ifdef CONFIG_ARM64
+ /*
+ * if SMC32 convention is used, pass 64 bit address in
+ * two parameters
+ */
+ if (!scmi_info->is_smc64)
There is no need for scmi_info to store is_smc64, just check the func_id
here and declare is_smc64 as a local variable to the function.
Also, another way to approach this would be to encode the parameters
region in 4KB units such that event on a 32-bit system with LPAE you are
guaranteed to fit the region into a 32-bit unsigned long. AFAIR
virtualization and LPAE are indistinguishable on real CPUs?
+ arm_smccc_1_1_invoke(scmi_info->func_id,
+ lower32(scmi_info->param),
+ upper32(scmi_info->param),
+ 0, 0, 0, 0, 0, &res);
+ else
+#endif
+ arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->param,
+ 0, 0, 0, 0, 0, 0, &res);
/* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
if (res.a0) {
--
Florian
