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x86/vdso: Add VCLOCK_HVCLOCK vDSO clock read method 

Hyper-V TSC page clocksource is suitable for vDSO, however, the protocol
defined by the hypervisor is different from VCLOCK_PVCLOCK. Implement the
required support by adding hvclock_page VVAR.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: devel@linuxdriverproject.org
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: virtualization@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20170303132142.25595-4-vkuznets@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Vitaly Kuznetsov 2017-03-03 14:21:42 +01:00 committed by Thomas Gleixner
parent 0733379b51
commit 90b20432ae
7 changed files with 42 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
arch/x86/entry/vdso/vclock_gettime.c
View File

@ -17,6 +17,7 @@
#include <asm/unistd.h>
#include <asm/msr.h>
#include <asm/pvclock.h>
#include <asm/mshyperv.h>
#include <linux/math64.h>
#include <linux/time.h>
#include <linux/kernel.h>
@ -32,6 +33,11 @@ extern u8 pvclock_page
__attribute__((visibility("hidden")));
#endif
#ifdef CONFIG_HYPERV_TSCPAGE
extern u8 hvclock_page
__attribute__((visibility("hidden")));
#endif
#ifndef BUILD_VDSO32
notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
@ -141,6 +147,20 @@ static notrace u64 vread_pvclock(int *mode)
return last;
}
#endif
#ifdef CONFIG_HYPERV_TSCPAGE
static notrace u64 vread_hvclock(int *mode)
{
const struct ms_hyperv_tsc_page *tsc_pg =
(const struct ms_hyperv_tsc_page *)&hvclock_page;
u64 current_tick = hv_read_tsc_page(tsc_pg);
if (current_tick != U64_MAX)
return current_tick;
*mode = VCLOCK_NONE;
return 0;
}
#endif
notrace static u64 vread_tsc(void)
{
@ -172,6 +192,10 @@ notrace static inline u64 vgetsns(int *mode)
#ifdef CONFIG_PARAVIRT_CLOCK
else if (gtod->vclock_mode == VCLOCK_PVCLOCK)
cycles = vread_pvclock(mode);
#endif
#ifdef CONFIG_HYPERV_TSCPAGE
else if (gtod->vclock_mode == VCLOCK_HVCLOCK)
cycles = vread_hvclock(mode);
#endif
else
return 0;

3
arch/x86/entry/vdso/vdso-layout.lds.S
View File

@ -25,7 +25,7 @@ SECTIONS
* segment.
*/
vvar_start = . - 2 * PAGE_SIZE;
vvar_start = . - 3 * PAGE_SIZE;
vvar_page = vvar_start;
/* Place all vvars at the offsets in asm/vvar.h. */
@ -36,6 +36,7 @@ SECTIONS
#undef EMIT_VVAR
pvclock_page = vvar_start + PAGE_SIZE;
hvclock_page = vvar_start + 2 * PAGE_SIZE;
. = SIZEOF_HEADERS;

3
arch/x86/entry/vdso/vdso2c.c
View File

@ -74,6 +74,7 @@ enum {
sym_vvar_page,
sym_hpet_page,
sym_pvclock_page,
sym_hvclock_page,
sym_VDSO_FAKE_SECTION_TABLE_START,
sym_VDSO_FAKE_SECTION_TABLE_END,
};
@ -82,6 +83,7 @@ const int special_pages[] = {
sym_vvar_page,
sym_hpet_page,
sym_pvclock_page,
sym_hvclock_page,
};
struct vdso_sym {
@ -94,6 +96,7 @@ struct vdso_sym required_syms[] = {
[sym_vvar_page] = {"vvar_page", true},
[sym_hpet_page] = {"hpet_page", true},
[sym_pvclock_page] = {"pvclock_page", true},
[sym_hvclock_page] = {"hvclock_page", true},
[sym_VDSO_FAKE_SECTION_TABLE_START] = {
"VDSO_FAKE_SECTION_TABLE_START", false
},

7
arch/x86/entry/vdso/vma.c
View File

@ -22,6 +22,7 @@
#include <asm/page.h>
#include <asm/desc.h>
#include <asm/cpufeature.h>
#include <asm/mshyperv.h>
#if defined(CONFIG_X86_64)
unsigned int __read_mostly vdso64_enabled = 1;
@ -121,6 +122,12 @@ static int vvar_fault(const struct vm_special_mapping *sm,
vmf->address,
__pa(pvti) >> PAGE_SHIFT);
}
} else if (sym_offset == image->sym_hvclock_page) {
struct ms_hyperv_tsc_page *tsc_pg = hv_get_tsc_page();
if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK))
ret = vm_insert_pfn(vma, vmf->address,
vmalloc_to_pfn(tsc_pg));
}
if (ret == 0 || ret == -EBUSY)

3
arch/x86/hyperv/hv_init.c
View File

@ -132,6 +132,9 @@ void hyperv_init(void)
tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
return;
}

3
arch/x86/include/asm/clocksource.h
View File

@ -6,7 +6,8 @@
#define VCLOCK_NONE 0 /* No vDSO clock available. */
#define VCLOCK_TSC 1 /* vDSO should use vread_tsc. */
#define VCLOCK_PVCLOCK 2 /* vDSO should use vread_pvclock. */
#define VCLOCK_MAX 2
#define VCLOCK_HVCLOCK 3 /* vDSO should use vread_hvclock. */
#define VCLOCK_MAX 3
struct arch_clocksource_data {
int vclock_mode;

1
arch/x86/include/asm/vdso.h
View File

@ -20,6 +20,7 @@ struct vdso_image {
long sym_vvar_page;
long sym_hpet_page;
long sym_pvclock_page;
long sym_hvclock_page;
long sym_VDSO32_NOTE_MASK;
long sym___kernel_sigreturn;
long sym___kernel_rt_sigreturn;