mirror of https://github.com/xemu-project/xemu.git
6787d27b04
In some cases, ibm,client-architecture-support calls can fail. This could happen in the current code for situations where the modified device tree segment exceeds the buffer size provided by the guest via the call parameters. In these cases, QEMU will reset, allowing an opportunity to regenerate the device tree from scratch via boot-time handling. There are potentially other scenarios as well, not currently reachable in the current code, but possible in theory, such as cases where device-tree properties or nodes need to be removed. We currently don't handle either of these properly for option vector capabilities however. Instead of carrying the negotiated capability beyond the reset and creating the boot-time device tree accordingly, we start from scratch, generating the same boot-time device tree as we did prior to the CAS-generated and the same device tree updates as we did before. This could (in theory) cause us to get stuck in a reset loop. This hasn't been observed, but depending on the extensiveness of CAS-induced device tree updates in the future, could eventually become an issue. Address this by pulling capability-related device tree updates resulting from CAS calls into a common routine, spapr_dt_cas_updates(), and adding an sPAPROptionVector* parameter that allows us to test for newly-negotiated capabilities. We invoke it as follows: 1) When ibm,client-architecture-support gets called, we call spapr_dt_cas_updates() with the set of capabilities added since the previous call to ibm,client-architecture-support. For the initial boot, or a system reset generated by something other than the CAS call itself, this set will consist of *all* options supported both the platform and the guest. For calls to ibm,client-architecture-support immediately after a CAS-induced reset, we call spapr_dt_cas_updates() with only the set of capabilities added since the previous call, since the other capabilities will have already been addressed by the boot-time device-tree this time around. In the unlikely event that capabilities are *removed* since the previous CAS, we will generate a CAS-induced reset. In the unlikely event that we cannot fit the device-tree updates into the buffer provided by the guest, well generate a CAS-induced reset. 2) When a CAS update results in the need to reset the machine and include the updates in the boot-time device tree, we call the spapr_dt_cas_updates() using the full set of negotiated capabilities as part of the reset path. At initial boot, or after a reset generated by something other than the CAS call itself, this set will be empty, resulting in what should be the same boot-time device-tree as we generated prior to this patch. For CAS-induced reset, this routine will be called with the full set of capabilities negotiated by the platform/guest in the previous CAS call, which should result in CAS updates from previous call being accounted for in the initial boot-time device tree. Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> [dwg: Changed an int -> bool conversion to be more explicit] Signed-off-by: David Gibson <david@gibson.dropbear.id.au> |
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| block | ||
| crypto | ||
| disas | ||
| exec | ||
| fpu | ||
| hw | ||
| io | ||
| libdecnumber | ||
| migration | ||
| monitor | ||
| net | ||
| qapi | ||
| qemu | ||
| qom | ||
| standard-headers | ||
| sysemu | ||
| ui | ||
| elf.h | ||
| glib-compat.h | ||
| qemu-common.h | ||
| qemu-io.h | ||
| trace-tcg.h | ||
| trace.h | ||