powerpc/pseries: Fix handling of PLPKS object flushing timeout

plpks_confirm_object_flushed() uses the H_PKS_CONFIRM_OBJECT_FLUSHED hcall
to check whether changes to an object in the Platform KeyStore have been
flushed to non-volatile storage.

The hcall returns two output values, the return code and the flush status.
plpks_confirm_object_flushed() polls the hcall until either the flush
status has updated, the return code is an error, or a timeout has been
exceeded.

While we're still polling, the hcall is returning H_SUCCESS (0) as the
return code. In the timeout case, this means that upon exiting the polling
loop, rc is 0, and therefore 0 is returned to the user.

Handle the timeout case separately and return ETIMEDOUT if triggered.

Fixes: 2454a7af0f2a ("powerpc/pseries: define driver for Platform KeyStore")
Reported-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Tested-by: Russell Currey <ruscur@russell.cc>
Reviewed-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230210080401.345462-2-ajd@linux.ibm.com

diff --git a/arch/powerpc/platforms/pseries/plpks.c b/arch/powerpc/platforms/pseries/plpks.c
index 4edd1585e24573b384ee8948f579646d4376aecf..9e85b6d85b0b25caf5e6da09731d5b28852b2a6c 100644 (file)
--- a/arch/powerpc/platforms/pseries/plpks.c
+++ b/arch/powerpc/platforms/pseries/plpks.c
@@ -248,6 +248,7 @@ static int plpks_confirm_object_flushed(struct label *label,
                                        struct plpks_auth *auth)
 {
        unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
+       bool timed_out = true;
        u64 timeout = 0;
        u8 status;
        int rc;
@@ -259,22 +260,26 @@ static int plpks_confirm_object_flushed(struct label *label,
 
                status = retbuf[0];
                if (rc) {
+                       timed_out = false;
                        if (rc == H_NOT_FOUND && status == 1)
                                rc = 0;
                        break;
                }
 
-               if (!rc && status == 1)
+               if (!rc && status == 1) {
+                       timed_out = false;
                        break;
+               }
 
                usleep_range(PKS_FLUSH_SLEEP,
                             PKS_FLUSH_SLEEP + PKS_FLUSH_SLEEP_RANGE);
                timeout = timeout + PKS_FLUSH_SLEEP;
        } while (timeout < PKS_FLUSH_MAX_TIMEOUT);
 
-       rc = pseries_status_to_err(rc);
+       if (timed_out)
+               return -ETIMEDOUT;
 
-       return rc;
+       return pseries_status_to_err(rc);
 }
 
 int plpks_write_var(struct plpks_var var)