powerpc/pseries: Use H_CLEAR_HPT to clear MMU hash table during kexec
An hcall was recently added that does exactly what we need during kexec
- it clears the entire MMU hash table, ignoring any VRMA mappings.
Try it and fall back to the old method if we get a failure.
On a POWER8 box with 5TB of memory, this reduces the time it takes to
kexec a new kernel from from 4 minutes to 1 minute.
Signed-off-by: Anton Blanchard <anton@samba.org>
Tested-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
[mpe: Split into separate functions and tweak function naming]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index aa35245..24ad43a 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -221,7 +221,7 @@
return -1;
}
-static void pSeries_lpar_hptab_clear(void)
+static void manual_hpte_clear_all(void)
{
unsigned long size_bytes = 1UL << ppc64_pft_size;
unsigned long hpte_count = size_bytes >> 4;
@@ -249,6 +249,26 @@
&(ptes[j].pteh), &(ptes[j].ptel));
}
}
+}
+
+static int hcall_hpte_clear_all(void)
+{
+ int rc;
+
+ do {
+ rc = plpar_hcall_norets(H_CLEAR_HPT);
+ } while (rc == H_CONTINUE);
+
+ return rc;
+}
+
+static void pseries_hpte_clear_all(void)
+{
+ int rc;
+
+ rc = hcall_hpte_clear_all();
+ if (rc != H_SUCCESS)
+ manual_hpte_clear_all();
#ifdef __LITTLE_ENDIAN__
/*
@@ -598,7 +618,7 @@
mmu_hash_ops.hpte_remove = pSeries_lpar_hpte_remove;
mmu_hash_ops.hpte_removebolted = pSeries_lpar_hpte_removebolted;
mmu_hash_ops.flush_hash_range = pSeries_lpar_flush_hash_range;
- mmu_hash_ops.hpte_clear_all = pSeries_lpar_hptab_clear;
+ mmu_hash_ops.hpte_clear_all = pseries_hpte_clear_all;
mmu_hash_ops.hugepage_invalidate = pSeries_lpar_hugepage_invalidate;
}