Provide catch-all error code to functions with paddr inputs

Functions which take physical addresses return SBI_ERR_INVALID_ADDRESS
for address parameters or address parameter plus size parameter inputs
which result in invalid physical addresses with respect to the
platform's physical memory layout and the RISC-V ISA. Also provide
these functions SBI_ERR_FAILED which may be used for addresses that
the specific SBI implementation does not support. It should be less
confusing to S-mode to get a generic error than an invalid address
error for addresses which S-mode is sure are valid (per the
platform/ISA).

Also add a new specification to return SBI_ERR_INVALID_ADDRESS for
invalid physical addresses and non-normative text stating when
SBI_ERR_FAILED may be returned instead.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>

src/binary-encoding.adoc

@@ -98,6 +98,20 @@ If an SBI function needs to pass a shared memory physical address range to
 the SBI implementation (or higher privilege mode), then this physical memory
 address range MUST satisfy the following requirements:
 
+* The SBI implementation MUST check that the specified physical memory range
+  is composed of valid physical addresses and return SBI_ERR_INVALID_ADDRESS
+  when any address in the range is not valid.
+
+NOTE: A valid address is one that only sets bits allowed by the platform's
+  physical memory layout and the RISC-V ISA. As an SBI implementation may
+  further restrict the allowed range, it may return a generic SBI_ERR_FAILED
+  (instead of SBI_ERR_INVALID_ADDRESS) when input is invalid with respect to
+  its specific limits. Returning SBI_ERR_FAILED instead of
+  SBI_ERR_INVALID_ADDRESS, in this case, is not a violation of the above
+  specification because the SBI implementation should detect the distinct case
+  of violating the more strict range first, making it appropriate to return the
+  error associated with the strict-range case immediately.
+
 * The SBI implementation MUST check that the supervisor-mode software is
   allowed to access the specified physical memory range with the access
   type requested (read and/or write).

src/ext-debug-triggers.adoc

@@ -121,6 +121,8 @@ The possible error codes returned in `sbiret.error` are shown in
                             and `shmem_phys_hi` parameters does not satisfy
                             the requirements described in
                             <<_shared_memory_physical_address_range_parameter>>.
+| SBI_ERR_FAILED          | The request failed for unspecified or unknown other
+                            reasons.
 |===
 
 === Function: Read triggers (FID #2)

src/ext-nested-acceleration.adoc

@@ -399,6 +399,8 @@ The possible error codes returned in `sbiret.error` are shown in
                             and `shmem_phys_hi` parameters does not satisfy
                             the requirements described in
                             <<_shared_memory_physical_address_range_parameter>>.
+| SBI_ERR_FAILED          | The request failed for unspecified or unknown other
+                            reasons.
 |===
 
 === Function: Synchronize shared memory CSRs (FID #2)

src/ext-pmu.adoc

@@ -585,6 +585,8 @@ The possible error codes returned in `sbiret.error` are shown in
                             and `shmem_phys_hi` parameters is not writable or
                             does not satisfy other requirements of
                             <<_shared_memory_physical_address_range_parameter>>.
+| SBI_ERR_FAILED          | The request failed for unspecified or unknown other
+                            reasons.
 |===
 
 === Function Listing

src/ext-sse.adoc

@@ -357,6 +357,8 @@ In case of an error, the possible error codes are shown in the
                             `output_phys_lo` and `output_phys_hi` parameters
                             does not satisfy the requirements described in
                             <<_shared_memory_physical_address_range_parameter>>.
+| SBI_ERR_FAILED          | The read failed for unspecified or unknown other
+                            reasons.
 |===
 
 === Function: Write software event attributes (FID #1)
@@ -402,6 +404,8 @@ The possible error codes returned in `sbiret.error` are shown in
                             `input_phys_lo` and `input_phys_hi` parameters
                             does not satisfy the requirements described in
                             <<_shared_memory_physical_address_range_parameter>>.
+| SBI_ERR_FAILED          | The write failed for unspecified or unknown other
+                            reasons.
 |===
 
 === Function: Register a software event (FID #2)