This adds support for using experimental hypercalls to change the size
of the main hash page table while running as a PAPR guest. For now these
hypercalls are only in experimental qemu versions.
The interface is two part: first H_RESIZE_HPT_PREPARE is used to allocate
and prepare the new hash table. This may be slow, but can be done
asynchronously. Then, H_RESIZE_HPT_COMMIT is used to switch to the new
hash table. This requires that no CPUs be concurrently updating the HPT,
and so must be run under stop_machine().
This patch only supplies a function to execute the hash table change,
nothing yet calls it.
Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
---
arch/powerpc/platforms/pseries/lpar.c | 109 ++++++++++++++++++++++++++++++++++
1 file changed, 109 insertions(+)
diff --git a/arch/powerpc/platforms/pseries/lpar.c
b/arch/powerpc/platforms/pseries/lpar.c
index b7a67e3..f6e7af5 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -27,6 +27,8 @@
#include <linux/console.h>
#include <linux/export.h>
#include <linux/jump_label.h>
+#include <linux/delay.h>
+#include <linux/stop_machine.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/page.h>
@@ -794,3 +796,110 @@ int h_get_mpp_x(struct hvcall_mpp_x_data *mpp_x_data)
return rc;
}
+
+#define HPT_RESIZE_TIMEOUT 10000 /* ms */
+
+struct hpt_resize_state {
+ unsigned long shift;
+ int commit_rc;
+};
+
+static int pseries_lpar_resize_hpt_commit(void *data)
+{
+ struct hpt_resize_state *state = data;
+
+ state->commit_rc = plpar_resize_hpt_commit(0, state->shift);
+ if (state->commit_rc != H_SUCCESS)
+ return -EIO;
+
+ /* Hypervisor has transitioned the HTAB, update our globals */
+ ppc64_pft_size = state->shift;
+ htab_size_bytes = 1UL << ppc64_pft_size;
+ htab_hash_mask = (htab_size_bytes >> 7) - 1;
+
+ return 0;
+}
+
+/* Must be called in user context */
+int pseries_lpar_resize_hpt(unsigned long shift)
+{
+ struct hpt_resize_state state = {
+ .shift = shift,
+ .commit_rc = H_FUNCTION,
+ };
+ unsigned int delay, total_delay = 0;
+ int rc;
+ ktime_t t0, t1, t2;
+
+ might_sleep();
+
+ if (!firmware_has_feature(FW_FEATURE_HPT_RESIZE))
+ return -ENODEV;
+
+ printk(KERN_INFO "lpar: Attempting to resize HPT to shift %lu\n",
+ shift);
+
+ t0 = ktime_get();
+
+ rc = plpar_resize_hpt_prepare(0, shift);
+ while (H_IS_LONG_BUSY(rc)) {
+ delay = get_longbusy_msecs(rc);
+ total_delay += delay;
+ if (total_delay > HPT_RESIZE_TIMEOUT) {
+ /* prepare call with shift==0 cancels an
+ * in-progress resize */
+ rc = plpar_resize_hpt_prepare(0, 0);
+ if (rc != H_SUCCESS)
+ printk(KERN_WARNING
+ "lpar: Unexpected error %d cancelling
timed out HPT resize\n",
+ rc);
+ return -ETIMEDOUT;
+ }
+ msleep(delay);
+ rc = plpar_resize_hpt_prepare(0, shift);
+ };
+
+ switch (rc) {
+ case H_SUCCESS:
+ /* Continue on */
+ break;
+
+ case H_PARAMETER:
+ return -EINVAL;
+ case H_RESOURCE:
+ return -EPERM;
+ default:
+ printk(KERN_WARNING
+ "lpar: Unexpected error %d from H_RESIZE_HPT_PREPARE\n",
+ rc);
+ return -EIO;
+ }
+
+ t1 = ktime_get();
+
+ rc = stop_machine(pseries_lpar_resize_hpt_commit, &state, NULL);
+
+ t2 = ktime_get();
+
+ if (rc != 0) {
+ switch (state.commit_rc) {
+ case H_PTEG_FULL:
+ printk(KERN_WARNING
+ "lpar: Hash collision while resizing HPT\n");
+ return -ENOSPC;
+
+ default:
+ printk(KERN_WARNING
+ "lpar: Unexpected error %d from
H_RESIZE_HPT_COMMIT\n",
+ state.commit_rc);
+ return -EIO;
+ };
+ }
+
+ printk(KERN_INFO
+ "lpar: HPT resize to shift %lu complete (%lld ms / %lld ms)\n",
+ shift, (long long) ktime_ms_delta(t1, t0),
+ (long long) ktime_ms_delta(t2, t1));
+
+ return 0;
+}
--
2.5.0
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