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x86: Add "nopv" parameter to disable PV extensions

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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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11
arch/x86/kernel/cpu/hypervisor.c
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@@ -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;