On Wed, May 30, 2018 at 11:58:54PM +0200, Martin Kletzander wrote:
On Wed, May 30, 2018 at 08:01:10PM +0200, Ján Tomko wrote:
>On Mon, May 21, 2018 at 05:00:53PM +0200, Martin Kletzander wrote:
>>Resolves:
https://bugzilla.redhat.com/show_bug.cgi?id=1469338
>>
>>Signed-off-by: Martin Kletzander <mkletzan(a)redhat.com>
>>---
>> src/qemu/qemu_command.c | 18 ++++
>> src/qemu/qemu_domain.c | 84 +++++++++++++++++++
>> .../qemuxml2argvdata/tseg-explicit-size.args | 28 +++++++
>> tests/qemuxml2argvdata/tseg-explicit-size.xml | 23 +++++
>> tests/qemuxml2argvdata/tseg-i440fx.xml | 23 +++++
>> tests/qemuxml2argvdata/tseg-invalid-size.xml | 23 +++++
>> .../tseg-old-machine-type.args | 27 ++++++
>> .../tseg-old-machine-type.xml | 21 +++++
>> tests/qemuxml2argvdata/tseg.args | 28 +++++++
>> tests/qemuxml2argvdata/tseg.xml | 21 +++++
>> tests/qemuxml2argvtest.c | 48 +++++++++++
>> .../qemuxml2xmloutdata/tseg-explicit-size.xml | 46 ++++++++++
>> .../tseg-old-machine-type.xml | 44 ++++++++++
>> tests/qemuxml2xmloutdata/tseg.xml | 46 ++++++++++
>> tests/qemuxml2xmltest.c | 25 ++++++
>> 15 files changed, 505 insertions(+)
>> create mode 100644 tests/qemuxml2argvdata/tseg-explicit-size.args
>> create mode 100644 tests/qemuxml2argvdata/tseg-explicit-size.xml
>> create mode 100644 tests/qemuxml2argvdata/tseg-i440fx.xml
>> create mode 100644 tests/qemuxml2argvdata/tseg-invalid-size.xml
>> create mode 100644 tests/qemuxml2argvdata/tseg-old-machine-type.args
>> create mode 100644 tests/qemuxml2argvdata/tseg-old-machine-type.xml
>> create mode 100644 tests/qemuxml2argvdata/tseg.args
>> create mode 100644 tests/qemuxml2argvdata/tseg.xml
>> create mode 100644 tests/qemuxml2xmloutdata/tseg-explicit-size.xml
>> create mode 100644 tests/qemuxml2xmloutdata/tseg-old-machine-type.xml
>> create mode 100644 tests/qemuxml2xmloutdata/tseg.xml
>>
>
>>diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
>>index 881d0ea46a75..3ea9e3d47344 100644
>>--- a/src/qemu/qemu_domain.c
>>+++ b/src/qemu/qemu_domain.c
>>@@ -3319,6 +3319,87 @@ qemuDomainDefCPUPostParse(virDomainDefPtr def)
[...]
>>+static int
>>+qemuDomainDefTsegPostParse(virDomainDefPtr def,
>>+ virQEMUCapsPtr qemuCaps)
>>+{
>>+ if (def->features[VIR_DOMAIN_FEATURE_SMM] != VIR_TRISTATE_SWITCH_ON)
>>+ return 0;
>>+
>>+ if (!def->tseg_size)
>>+ return qemuDomainSetDefaultTsegSize(def, qemuCaps);
>>+
>>+ if (!qemuDomainIsQ35(def)) {
>>+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>>+ _("SMM TSEG is only supported with q35 machine
type"));
>>+ return -1;
>>+ }
>>+
>>+ if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_MCH_EXTENDED_TSEG_MBYTES)) {
>>+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>>+ _("Setting TSEG size is not supported with this QEMU
binary"));
>>+ return -1;
>>+ }
>>+
>>+ if (VIR_ROUND_UP(def->tseg_size, 1024 * 1024) != def->tseg_size) {
>
>Interesting way of writing the % operator.
>
More like very interesting brainfart [1] I had there. I mean I almost open-coded
the VIR_ROUND_UP at first and haven't even thought about anything else. Wow.
Actually, in the resulting assembly (comparing -O2) it both streches across 5
lines that are very weirdly different/similar. What's way faster is:
if (def->tseg_size & ((1<<20) - 1))
which just expands to
xorl %eax, %eax
andl $1048575, %edi
and to make it even more confusing, the previous two approaches share the `andl`
line with this one. Scary.
[1] And that's very weak word for this particular "thing".