[libvirt] [RFC PATCH 6/6] qemu: Format pseries.cap-hpt-mps on the command line

[Andrea Bolognani]

This makes the feature fully functional.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1571078

Signed-off-by: Andrea Bolognani <abologna at redhat.com>
---
 src/qemu/qemu_command.c                      | 26 ++++++++++++++++++++
 tests/qemuxml2argvdata/pseries-features.args |  3 ++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index b446a08613..983839e81c 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -7193,6 +7193,32 @@ qemuBuildMachineCommandLine(virCommandPtr cmd,
 
             virBufferAsprintf(&buf, ",resize-hpt=%s", str);
         }
+
+        if (def->hpt_maxpagesize > 0) {
+            unsigned long long tmp = def->hpt_maxpagesize;
+            unsigned int shifts = 0;
+
+            if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_MACHINE_PSERIES_CAP_HPT_MPS)) {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                               _("Limiting the page size for HPT guest is "
+                                 "not supported by this QEMU binary"));
+                goto cleanup;
+            }
+
+            /* QEMU expects the argument to be a number of left shifts:
+             * for example, if you wanted to limit the guest to 4 KiB pages,
+             * since 4096 == 1 << 12, you would need to add cap-hpt-mps=12
+             * to the command line.
+             *
+             * Convert from our internal representation, which is bytes,
+             * to the one QEMU expects */
+            while (tmp > 1) {
+                tmp = tmp >> 1;
+                shifts++;
+            }
+
+            virBufferAsprintf(&buf, ",cap-hpt-mps=%u", shifts);
+        }
     }
 
     if (cpu && cpu->model &&
diff --git a/tests/qemuxml2argvdata/pseries-features.args b/tests/qemuxml2argvdata/pseries-features.args
index f5c1959cca..4e581a69a1 100644
--- a/tests/qemuxml2argvdata/pseries-features.args
+++ b/tests/qemuxml2argvdata/pseries-features.args
@@ -7,7 +7,8 @@ QEMU_AUDIO_DRV=none \
 /usr/bin/qemu-system-ppc64 \
 -name guest \
 -S \
--machine pseries,accel=tcg,usb=off,dump-guest-core=off,resize-hpt=required \
+-machine pseries,accel=tcg,usb=off,dump-guest-core=off,resize-hpt=required,\
+cap-hpt-mps=30 \
 -m 512 \
 -smp 1,sockets=1,cores=1,threads=1 \
 -uuid 1ccfd97d-5eb4-478a-bbe6-88d254c16db7 \
-- 
2.17.0