When binding an SCM volume to a physical address the hypervisor has the option to return early with a continue token with the expectation that the guest will resume the bind operation until it completes. A quirk of this interface is that the bind address will only be returned by the first bind h-call and the subsequent calls will return 0xFFFF_FFFF_FFFF_FFFF for the bind address.
We currently do not save the address returned by the first h-call. As a result we will use the junk address as the base of the bound region if the hypervisor decides to split the bind across multiple h-calls. This bug was found when testing with very large SCM volumes where the bind process would take more time than they hypervisor's internal h-call time limit would allow. This patch fixes the issue by saving the bind address from the first call.
Cc: stable@vger.kernel.org Fixes: b5beae5e224f ("powerpc/pseries: Add driver for PAPR SCM regions") Signed-off-by: Oliver O'Halloran oohall@gmail.com --- arch/powerpc/platforms/pseries/papr_scm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c index 7d6457ab5d34..bba281b1fe1b 100644 --- a/arch/powerpc/platforms/pseries/papr_scm.c +++ b/arch/powerpc/platforms/pseries/papr_scm.c @@ -43,6 +43,7 @@ static int drc_pmem_bind(struct papr_scm_priv *p) { unsigned long ret[PLPAR_HCALL_BUFSIZE]; uint64_t rc, token; + uint64_t saved = 0;
/* * When the hypervisor cannot map all the requested memory in a single @@ -56,6 +57,8 @@ static int drc_pmem_bind(struct papr_scm_priv *p) rc = plpar_hcall(H_SCM_BIND_MEM, ret, p->drc_index, 0, p->blocks, BIND_ANY_ADDR, token); token = ret[0]; + if (!saved) + saved = ret[1]; cond_resched(); } while (rc == H_BUSY);
@@ -64,7 +67,7 @@ static int drc_pmem_bind(struct papr_scm_priv *p) return -ENXIO; }
- p->bound_addr = ret[1]; + p->bound_addr = saved;
dev_dbg(&p->pdev->dev, "bound drc %x to %pR\n", p->drc_index, &p->res);