From 07b10bc42cc83a49acaa783383a69fb59d7ff71a Mon Sep 17 00:00:00 2001 From: Daniel Henrique Barboza Date: Thu, 10 Dec 2020 11:55:17 -0300 Subject: spapr.c: set a 'kvm-type' default value instead of relying on NULL spapr_kvm_type() is considering 'vm_type=NULL' as a valid input, where the function returns 0. This is relying on the current QEMU machine options handling logic, where the absence of the 'kvm-type' option will be reflected as 'vm_type=NULL' in this function. This is not robust, and will break if QEMU options code decides to propagate something else in the case mentioned above (e.g. an empty string instead of NULL). Let's avoid this entirely by setting a non-NULL default value in case of no user input for 'kvm-type'. spapr_kvm_type() was changed to handle 3 fixed values of kvm-type: "auto", "hv", and "pr", with "auto" being the default if no kvm-type was set by the user. This allows us to always be predictable regardless of any enhancements/changes made in QEMU options mechanics. While we're at it, let's also document in 'kvm-type' description the already existing default mode, now named 'auto'. The information provided about it is based on how the pseries kernel handles the KVM_CREATE_VM ioctl(), where the default value '0' makes the kernel choose an available KVM module to use, giving precedence to kvm_hv. This logic is described in the kernel source file arch/powerpc/kvm/powerpc.c, function kvm_arch_init_vm(). Signed-off-by: Daniel Henrique Barboza Message-Id: <20201210145517.1532269-2-danielhb413@gmail.com> Signed-off-by: David Gibson Reviewed-by: Greg Kurz --- hw/ppc/spapr.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index dfedded9a8..dee48a0043 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -3021,17 +3021,25 @@ static void spapr_machine_init(MachineState *machine) qemu_cond_init(&spapr->fwnmi_machine_check_interlock_cond); } +#define DEFAULT_KVM_TYPE "auto" static int spapr_kvm_type(MachineState *machine, const char *vm_type) { - if (!vm_type) { + /* + * The use of g_ascii_strcasecmp() for 'hv' and 'pr' is to + * accomodate the 'HV' and 'PV' formats that exists in the + * wild. The 'auto' mode is being introduced already as + * lower-case, thus we don't need to bother checking for + * "AUTO". + */ + if (!vm_type || !strcmp(vm_type, DEFAULT_KVM_TYPE)) { return 0; } - if (!strcmp(vm_type, "HV")) { + if (!g_ascii_strcasecmp(vm_type, "hv")) { return 1; } - if (!strcmp(vm_type, "PR")) { + if (!g_ascii_strcasecmp(vm_type, "pr")) { return 2; } @@ -3270,10 +3278,15 @@ static void spapr_instance_init(Object *obj) spapr->htab_fd = -1; spapr->use_hotplug_event_source = true; + spapr->kvm_type = g_strdup(DEFAULT_KVM_TYPE); object_property_add_str(obj, "kvm-type", spapr_get_kvm_type, spapr_set_kvm_type); object_property_set_description(obj, "kvm-type", - "Specifies the KVM virtualization mode (HV, PR)"); + "Specifies the KVM virtualization mode (auto," + " hv, pr). Defaults to 'auto'. This mode will use" + " any available KVM module loaded in the host," + " where kvm_hv takes precedence if both kvm_hv and" + " kvm_pr are loaded."); object_property_add_bool(obj, "modern-hotplug-events", spapr_get_modern_hotplug_events, spapr_set_modern_hotplug_events); -- cgit v1.2.3-55-g7522