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Commit 30978346 authored by Zhenzhong Duan's avatar Zhenzhong Duan Committed by Juergen Gross
Browse files

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: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarZhenzhong Duan <zhenzhong.duan@oracle.com>
Reviewed-by: default avatarJuergen 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: default avatarJuergen Gross <jgross@suse.com>
parent 1b37683c

Documentation/admin-guide/kernel-parameters.txt

+5 −0
Original line number Diff line number Diff line
@@ -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>]]]

arch/x86/include/asm/hypervisor.h

+4 −0
Original line number Diff line number Diff line
@@ -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)

arch/x86/kernel/cpu/hypervisor.c

+11 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/kernel/jailhouse.c

+1 −0
Original line number Diff line number Diff line
@@ -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,

};

arch/x86/xen/enlighten_pv.c

+1 −0
Original line number Diff line number Diff line
@@ -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,

};