[Libguestfs] [PATCH] always 'max' for the appliance CPU model on all targes except ppc
Daniel P. Berrangé
berrange at redhat.com
Wed May 25 13:30:29 UTC 2022
The current logic for selecting CPU model to use with the appliance
selects 'max' for all architectures except for ppc64le and aarch64.
On aarch64, it selects 'host' if KVM is available which is identical
to 'max'. For TCG it selects 'cortex-a57'. The 'max' model is a
superset of 'cortex-a57', so it is reasonable to use 'max' for TCG
too.
On ppc64, it selects no CPU model due to a historical bug where
using 'host' would break ability to fallback to TCG. Unfortunately
we can't use 'max' on PPC as this is actually an old G4 vintage
32-bit model, rather than a synonym for 'host' / all-TCG-features
as on other targets.
We can at least simplify the code to use 'max' in all scenarios
for appliance CPU model, and simply skip a CPU model for PPC.
Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
---
docs/C_SOURCE_FILES | 1 -
lib/Makefile.am | 1 -
lib/appliance-cpu.c | 93 ------------------------------------------
lib/guestfs-internal.h | 3 --
lib/launch-direct.c | 25 +++++-------
lib/launch-libvirt.c | 40 ++++++++----------
po/POTFILES | 1 -
7 files changed, 27 insertions(+), 137 deletions(-)
delete mode 100644 lib/appliance-cpu.c
diff --git a/docs/C_SOURCE_FILES b/docs/C_SOURCE_FILES
index a367c93a0..a26487d99 100644
--- a/docs/C_SOURCE_FILES
+++ b/docs/C_SOURCE_FILES
@@ -283,7 +283,6 @@ lib/actions-6.c
lib/actions-support.c
lib/actions-variants.c
lib/alloc.c
-lib/appliance-cpu.c
lib/appliance-kcmdline.c
lib/appliance-uefi.c
lib/appliance.c
diff --git a/lib/Makefile.am b/lib/Makefile.am
index 212bcb94a..40a4c9ac3 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -71,7 +71,6 @@ libguestfs_la_SOURCES = \
actions-variants.c \
alloc.c \
appliance.c \
- appliance-cpu.c \
appliance-kcmdline.c \
appliance-uefi.c \
available.c \
diff --git a/lib/appliance-cpu.c b/lib/appliance-cpu.c
deleted file mode 100644
index 54ac6e2e3..000000000
--- a/lib/appliance-cpu.c
+++ /dev/null
@@ -1,93 +0,0 @@
-/* libguestfs
- * Copyright (C) 2009-2020 Red Hat Inc.
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-/**
- * The appliance choice of CPU model.
- */
-
-#include <config.h>
-
-#include <stdio.h>
-#include <stdlib.h>
-
-#include "guestfs.h"
-#include "guestfs-internal.h"
-
-/**
- * Return the right CPU model to use as the qemu C<-cpu> parameter or
- * its equivalent in libvirt. This returns:
- *
- * =over 4
- *
- * =item C<"host">
- *
- * The literal string C<"host"> means use C<-cpu host>.
- *
- * =item C<"max">
- *
- * The literal string C<"max"> means use C<-cpu max> (the best
- * possible). This requires awkward translation for libvirt.
- *
- * =item some string
- *
- * Some string such as C<"cortex-a57"> means use C<-cpu cortex-a57>.
- *
- * =item C<NULL>
- *
- * C<NULL> means no C<-cpu> option at all. Note returning C<NULL>
- * does not indicate an error.
- *
- * =back
- *
- * This is made unnecessarily hard and fragile because of two stupid
- * choices in QEMU:
- *
- * =over 4
- *
- * =item *
- *
- * The default for C<qemu-system-aarch64 -M virt> is to emulate a
- * C<cortex-a15> (WTF?).
- *
- * =item *
- *
- * We don't know for sure if KVM will work, but C<-cpu host> is broken
- * with TCG, so we almost always pass a broken C<-cpu> flag if KVM is
- * semi-broken in any way.
- *
- * =back
- */
-const char *
-guestfs_int_get_cpu_model (int kvm)
-{
-#if defined(__aarch64__)
- /* With -M virt, the default -cpu is cortex-a15. Stupid. */
- if (kvm)
- return "host";
- else
- return "cortex-a57";
-#elif defined(__powerpc64__)
- /* See discussion in https://bugzilla.redhat.com/show_bug.cgi?id=1605071 */
- return NULL;
-#else
- /* On most architectures we can use "max" to get the best possible CPU.
- * For recent qemu this should work even on TCG.
- */
- return "max";
-#endif
-}
diff --git a/lib/guestfs-internal.h b/lib/guestfs-internal.h
index 16755cfb3..33037a26d 100644
--- a/lib/guestfs-internal.h
+++ b/lib/guestfs-internal.h
@@ -718,9 +718,6 @@ extern const char *guestfs_int_drive_protocol_to_string (enum drive_protocol pro
/* appliance.c */
extern int guestfs_int_build_appliance (guestfs_h *g, char **kernel, char **initrd, char **appliance);
-/* appliance-cpu.c */
-const char *guestfs_int_get_cpu_model (int kvm);
-
/* appliance-kcmdline.c */
extern char *guestfs_int_appliance_command_line (guestfs_h *g, const char *appliance, int flags);
#define APPLIANCE_COMMAND_LINE_IS_TCG 1
diff --git a/lib/launch-direct.c b/lib/launch-direct.c
index ff0eaeb62..f41711353 100644
--- a/lib/launch-direct.c
+++ b/lib/launch-direct.c
@@ -354,7 +354,6 @@ launch_direct (guestfs_h *g, void *datav, const char *arg)
int force_tcg;
int force_kvm;
const char *accel_val = "kvm:tcg";
- const char *cpu_model;
CLEANUP_FREE char *append = NULL;
CLEANUP_FREE_STRING_LIST char **argv = NULL;
@@ -517,20 +516,18 @@ launch_direct (guestfs_h *g, void *datav, const char *arg)
#endif
} end_list ();
- cpu_model = guestfs_int_get_cpu_model (has_kvm && !force_tcg);
- if (cpu_model) {
-#if defined(__x86_64__)
- /* Temporary workaround for RHBZ#2082806 */
- if (STREQ (cpu_model, "max")) {
- start_list ("-cpu") {
- append_list (cpu_model);
- append_list ("la57=off");
- } end_list ();
- }
- else
+ /*
+ * Can't use 'max' on ppc64 since it is an old G4 model
+ * Also can't use 'host' due to TCG fallback issues
+ * https://bugzilla.redhat.com/show_bug.cgi?id=1605071
+ */
+#if !defined(__powerpc64__)
+# if defined(__x86_64__)
+ arg ("-cpu", "max,la57=off");
+# else
+ arg ("-cpu", "max");
+# endif
#endif
- arg ("-cpu", cpu_model);
- }
if (g->smp > 1)
arg_format ("-smp", "%d", g->smp);
diff --git a/lib/launch-libvirt.c b/lib/launch-libvirt.c
index 03d69e027..b97c91566 100644
--- a/lib/launch-libvirt.c
+++ b/lib/launch-libvirt.c
@@ -1161,8 +1161,6 @@ construct_libvirt_xml_cpu (guestfs_h *g,
const struct libvirt_xml_params *params,
xmlTextWriterPtr xo)
{
- const char *cpu_model;
-
start_element ("memory") {
attribute ("unit", "MiB");
string_format ("%d", g->memsize);
@@ -1173,30 +1171,24 @@ construct_libvirt_xml_cpu (guestfs_h *g,
string_format ("%d", g->memsize);
} end_element ();
- cpu_model = guestfs_int_get_cpu_model (params->data->is_kvm);
- if (cpu_model) {
- start_element ("cpu") {
- if (STREQ (cpu_model, "host")) {
- attribute ("mode", "host-passthrough");
- start_element ("model") {
- attribute ("fallback", "allow");
- } end_element ();
- }
- else if (STREQ (cpu_model, "max")) {
- /* https://bugzilla.redhat.com/show_bug.cgi?id=1935572#c11 */
- attribute ("mode", "maximum");
+ /*
+ * Can't use 'max' on ppc64 since it is an old G4 model
+ * Also can't use 'host' due to TCG fallback issues
+ * https://bugzilla.redhat.com/show_bug.cgi?id=1605071
+ */
+#if !defined(__powerpc64__)
+ start_element ("cpu") {
+ /* https://bugzilla.redhat.com/show_bug.cgi?id=1935572#c11 */
+ attribute ("mode", "maximum");
#if defined(__x86_64__)
- /* Temporary workaround for RHBZ#2082806 */
- start_element ("feature") {
- attribute ("policy", "disable");
- attribute ("name", "la57");
- } end_element ();
-#endif
- }
- else
- single_element ("model", cpu_model);
+ /* Temporary workaround for RHBZ#2082806 */
+ start_element ("feature") {
+ attribute ("policy", "disable");
+ attribute ("name", "la57");
} end_element ();
- }
+#endif
+ } end_element ();
+#endif
single_element_format ("vcpu", "%d", g->smp);
diff --git a/po/POTFILES b/po/POTFILES
index 32b975a04..67cdffb29 100644
--- a/po/POTFILES
+++ b/po/POTFILES
@@ -329,7 +329,6 @@ lib/actions-6.c
lib/actions-support.c
lib/actions-variants.c
lib/alloc.c
-lib/appliance-cpu.c
lib/appliance-kcmdline.c
lib/appliance-uefi.c
lib/appliance.c
--
2.36.1
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