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x86: Add "nopv" parameter to disable PV extensions 

In virtualization environment, PV extensions (drivers, interrupts,
timers, etc) are enabled in the majority of use cases which is the
best option.

However, in some cases (kexec not fully working, benchmarking)
we want to disable PV extensions. We have "xen_nopv" for that purpose
but only for XEN. For a consistent admin experience a common command
line parameter "nopv" set across all PV guest implementations is a
better choice.

There are guest types which just won't work without PV extensions,
like Xen PV, Xen PVH and jailhouse. add a "ignore_nopv" member to
struct hypervisor_x86 set to true for those guest types and call
the detect functions only if nopv is false or ignore_nopv is true.

Suggested-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Zhenzhong Duan 2019-07-11 20:02:09 +08:00 committed by Juergen Gross
parent 1b37683cda
commit 3097834637
5 changed files with 22 additions and 0 deletions
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5
Documentation/admin-guide/kernel-parameters.txt
View File

@ -5257,6 +5257,11 @@
improve timer resolution at the expense of processing
more timer interrupts.
nopv= [X86,XEN,KVM,HYPER_V,VMWARE]
Disables the PV optimizations forcing the guest to run
as generic guest with no PV drivers. Currently support
XEN HVM, KVM, HYPER_V and VMWARE guest.
xirc2ps_cs= [NET,PCMCIA]
Format:
<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]

4
arch/x86/include/asm/hypervisor.h
View File

@ -53,8 +53,12 @@ struct hypervisor_x86 {
/* runtime callbacks */
struct x86_hyper_runtime runtime;
/* ignore nopv parameter */
bool ignore_nopv;
};
extern bool nopv;
extern enum x86_hypervisor_type x86_hyper_type;
extern void init_hypervisor_platform(void);
static inline bool hypervisor_is_type(enum x86_hypervisor_type type)

11
arch/x86/kernel/cpu/hypervisor.c
View File

@ -58,6 +58,14 @@ static const __initconst struct hypervisor_x86 * const hypervisors[] =
enum x86_hypervisor_type x86_hyper_type;
EXPORT_SYMBOL(x86_hyper_type);
bool __initdata nopv;
static __init int parse_nopv(char *arg)
{
nopv = true;
return 0;
}
early_param("nopv", parse_nopv);
static inline const struct hypervisor_x86 * __init
detect_hypervisor_vendor(void)
{
@ -65,6 +73,9 @@ detect_hypervisor_vendor(void)
uint32_t pri, max_pri = 0;
for (p = hypervisors; p < hypervisors + ARRAY_SIZE(hypervisors); p++) {
if (unlikely(nopv) && !(*p)->ignore_nopv)
continue;
pri = (*p)->detect();
if (pri > max_pri) {
max_pri = pri;

1
arch/x86/kernel/jailhouse.c
View File

@ -217,4 +217,5 @@ const struct hypervisor_x86 x86_hyper_jailhouse __refconst = {
.detect = jailhouse_detect,
.init.init_platform = jailhouse_init_platform,
.init.x2apic_available = jailhouse_x2apic_available,
.ignore_nopv = true,
};

1
arch/x86/xen/enlighten_pv.c
View File

@ -1463,4 +1463,5 @@ const __initconst struct hypervisor_x86 x86_hyper_xen_pv = {
.detect = xen_platform_pv,
.type = X86_HYPER_XEN_PV,
.runtime.pin_vcpu = xen_pin_vcpu,
.ignore_nopv = true,
};