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pvclock: Add vDSO support

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Add vDSO support for timekeeping devices that support the KVM/XEN
paravirtual clock API.

Also, expose, in the userspace-accessible '<machine/pvclock.h>',
definitions that will be needed by 'libc' to support
'VDSO_TH_ALGO_X86_PVCLK'.

Sponsored by:	Juniper Networks, Inc.
Sponsored by:	Klara, Inc.
Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D31418
This commit is contained in:
Adam Fenn 2021-08-07 13:10:04 -07:00 committed by Konstantin Belousov
parent 6c69c6bb4c
commit d4b2d3035a
6 changed files with 188 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
sys/dev/acpica/acpi_hpet.c
View File

@ -156,6 +156,8 @@ hpet_vdso_timehands(struct vdso_timehands *vdso_th, struct timecounter *tc)
vdso_th->th_algo = VDSO_TH_ALGO_X86_HPET;
vdso_th->th_x86_shift = 0;
vdso_th->th_x86_hpet_idx = device_get_unit(sc->dev);
vdso_th->th_x86_pvc_last_systime = 0;
vdso_th->th_x86_pvc_stable_mask = 0;
bzero(vdso_th->th_res, sizeof(vdso_th->th_res));
return (sc->mmap_allow != 0);
}
@ -171,6 +173,8 @@ hpet_vdso_timehands32(struct vdso_timehands32 *vdso_th32,
vdso_th32->th_algo = VDSO_TH_ALGO_X86_HPET;
vdso_th32->th_x86_shift = 0;
vdso_th32->th_x86_hpet_idx = device_get_unit(sc->dev);
vdso_th32->th_x86_pvc_last_systime = 0;
vdso_th32->th_x86_pvc_stable_mask = 0;
bzero(vdso_th32->th_res, sizeof(vdso_th32->th_res));
return (sc->mmap_allow != 0);
}

2
sys/dev/hyperv/vmbus/amd64/hyperv_machdep.c
View File

@ -128,6 +128,8 @@ hyperv_tsc_vdso_timehands(struct vdso_timehands *vdso_th,
vdso_th->th_algo = VDSO_TH_ALGO_X86_HVTSC;
vdso_th->th_x86_shift = 0;
vdso_th->th_x86_hpet_idx = 0;
vdso_th->th_x86_pvc_last_systime = 0;
vdso_th->th_x86_pvc_stable_mask = 0;
bzero(vdso_th->th_res, sizeof(vdso_th->th_res));
return (1);
}

62
sys/x86/include/pvclock.h
View File

@ -30,7 +30,12 @@
#define X86_PVCLOCK
#include <sys/types.h>
#ifdef _KERNEL
#include <sys/timetc.h>
#endif /* _KERNEL */
#define PVCLOCK_CDEVNAME "pvclock"
struct pvclock_vcpu_time_info {
uint32_t version;
@ -46,6 +51,59 @@ struct pvclock_vcpu_time_info {
#define PVCLOCK_FLAG_TSC_STABLE 0x01
#define PVCLOCK_FLAG_GUEST_PASUED 0x02
/*
* Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
* yielding a 64-bit result.
*/
static inline uint64_t
pvclock_scale_delta(uint64_t delta, uint32_t mul_frac, int shift)
{
uint64_t product;
if (shift < 0)
delta >>= -shift;
else
delta <<= shift;
#if defined(__i386__)
{
uint32_t tmp1, tmp2;
/**
* For i386, the formula looks like:
*
* lower = (mul_frac * (delta & UINT_MAX)) >> 32
* upper = mul_frac * (delta >> 32)
* product = lower + upper
*/
__asm__ (
"mul %5 ; "
"mov %4,%%eax ; "
"mov %%edx,%4 ; "
"mul %5 ; "
"xor %5,%5 ; "
"add %4,%%eax ; "
"adc %5,%%edx ; "
: "=A" (product), "=r" (tmp1), "=r" (tmp2)
: "a" ((uint32_t)delta), "1" ((uint32_t)(delta >> 32)),
"2" (mul_frac) );
}
#elif defined(__amd64__)
{
unsigned long tmp;
__asm__ (
"mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
: [lo]"=a" (product), [hi]"=d" (tmp)
: "0" (delta), [mul_frac]"rm"((uint64_t)mul_frac));
}
#else
#error "pvclock: unsupported x86 architecture?"
#endif
return (product);
}
#ifdef _KERNEL
typedef struct pvclock_wall_clock *pvclock_get_wallclock_t(void *arg);
struct pvclock_wall_clock {
@ -62,7 +120,9 @@ struct pvclock {
bool stable_flag_supported;
/* Private; initialized by the 'pvclock' API: */
bool vdso_force_unstable;
struct timecounter tc;
struct cdev *cdev;
};
/*
@ -81,4 +141,6 @@ void pvclock_init(struct pvclock *pvc, device_t dev,
void pvclock_gettime(struct pvclock *pvc, struct timespec *ts);
int pvclock_destroy(struct pvclock *pvc);
#endif /* _KERNEL */
#endif

5
sys/x86/include/vdso.h
View File

@ -37,11 +37,14 @@
#define VDSO_TIMEHANDS_MD \
uint32_t th_x86_shift; \
uint32_t th_x86_hpet_idx; \
uint32_t th_res[6];
uint64_t th_x86_pvc_last_systime;\
uint8_t th_x86_pvc_stable_mask; \
uint8_t th_res[15];
#define VDSO_TH_ALGO_X86_TSC VDSO_TH_ALGO_1
#define VDSO_TH_ALGO_X86_HPET VDSO_TH_ALGO_2
#define VDSO_TH_ALGO_X86_HVTSC VDSO_TH_ALGO_3 /* Hyper-V ref. TSC */
#define VDSO_TH_ALGO_X86_PVCLK VDSO_TH_ALGO_4 /* KVM/XEN paravirtual clock */
#ifdef _KERNEL
#ifdef COMPAT_FREEBSD32

165
sys/x86/x86/pvclock.c
View File

@ -31,11 +31,22 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/clock.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/limits.h>
#include <sys/mman.h>
#include <sys/proc.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/vdso.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <machine/atomic.h>
#include <machine/cpufunc.h>
#include <machine/md_var.h>
#include <machine/pvclock.h>
@ -54,6 +65,22 @@ static void pvclock_read_time_info(
static void pvclock_read_wall_clock(struct pvclock_wall_clock *wc,
struct timespec *ts);
static u_int pvclock_tc_get_timecount(struct timecounter *tc);
static uint32_t pvclock_tc_vdso_timehands(
struct vdso_timehands *vdso_th, struct timecounter *tc);
#ifdef COMPAT_FREEBSD32
static uint32_t pvclock_tc_vdso_timehands32(
struct vdso_timehands32 *vdso_th, struct timecounter *tc);
#endif
static d_open_t pvclock_cdev_open;
static d_mmap_t pvclock_cdev_mmap;
static struct cdevsw pvclock_cdev_cdevsw = {
.d_version = D_VERSION,
.d_name = PVCLOCK_CDEVNAME,
.d_open = pvclock_cdev_open,
.d_mmap = pvclock_cdev_mmap,
};
void
pvclock_resume(void)
@ -74,57 +101,6 @@ pvclock_tsc_freq(struct pvclock_vcpu_time_info *ti)
return (freq);
}
/*
* Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
* yielding a 64-bit result.
*/
static inline uint64_t
pvclock_scale_delta(uint64_t delta, uint32_t mul_frac, int shift)
{
uint64_t product;
if (shift < 0)
delta >>= -shift;
else
delta <<= shift;
#if defined(__i386__)
{
uint32_t tmp1, tmp2;
/**
* For i386, the formula looks like:
*
* lower = (mul_frac * (delta & UINT_MAX)) >> 32
* upper = mul_frac * (delta >> 32)
* product = lower + upper
*/
__asm__ (
"mul %5 ; "
"mov %4,%%eax ; "
"mov %%edx,%4 ; "
"mul %5 ; "
"xor %5,%5 ; "
"add %4,%%eax ; "
"adc %5,%%edx ; "
: "=A" (product), "=r" (tmp1), "=r" (tmp2)
: "a" ((uint32_t)delta), "1" ((uint32_t)(delta >> 32)),
"2" (mul_frac) );
}
#elif defined(__amd64__)
{
unsigned long tmp;
__asm__ (
"mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
: [lo]"=a" (product), [hi]"=d" (tmp)
: "0" (delta), [mul_frac]"rm"((uint64_t)mul_frac));
}
#else
#error "pvclock: unsupported x86 architecture?"
#endif
return (product);
}
static void
pvclock_read_time_info(struct pvclock_vcpu_time_info *ti,
uint64_t *ns, uint8_t *flags)
@ -213,6 +189,27 @@ pvclock_get_wallclock(struct pvclock_wall_clock *wc, struct timespec *ts)
pvclock_read_wall_clock(wc, ts);
}
static int
pvclock_cdev_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
{
if (oflags & FWRITE)
return (EPERM);
return (0);
}
static int
pvclock_cdev_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
int nprot, vm_memattr_t *memattr)
{
if (offset >= mp_ncpus * sizeof(struct pvclock_vcpu_time_info))
return (EINVAL);
if (PROT_EXTRACT(nprot) != PROT_READ)
return (EACCES);
*paddr = vtophys((uintptr_t)dev->si_drv1 + offset);
*memattr = VM_MEMATTR_DEFAULT;
return (0);
}
static u_int
pvclock_tc_get_timecount(struct timecounter *tc)
{
@ -221,6 +218,42 @@ pvclock_tc_get_timecount(struct timecounter *tc)
return (pvclock_getsystime(pvc) & UINT_MAX);
}
static uint32_t
pvclock_tc_vdso_timehands(struct vdso_timehands *vdso_th,
struct timecounter *tc)
{
struct pvclock *pvc = tc->tc_priv;
vdso_th->th_algo = VDSO_TH_ALGO_X86_PVCLK;
vdso_th->th_x86_shift = 0;
vdso_th->th_x86_hpet_idx = 0;
vdso_th->th_x86_pvc_last_systime =
atomic_load_acq_64(&pvclock_last_systime);
vdso_th->th_x86_pvc_stable_mask = !pvc->vdso_force_unstable &&
pvc->stable_flag_supported ? PVCLOCK_FLAG_TSC_STABLE : 0;
bzero(vdso_th->th_res, sizeof(vdso_th->th_res));
return (pvc->cdev != NULL && amd_feature & AMDID_RDTSCP);
}
#ifdef COMPAT_FREEBSD32
static uint32_t
pvclock_tc_vdso_timehands32(struct vdso_timehands32 *vdso_th,
struct timecounter *tc)
{
struct pvclock *pvc = tc->tc_priv;
vdso_th->th_algo = VDSO_TH_ALGO_X86_PVCLK;
vdso_th->th_x86_shift = 0;
vdso_th->th_x86_hpet_idx = 0;
vdso_th->th_x86_pvc_last_systime =
atomic_load_acq_64(&pvclock_last_systime);
vdso_th->th_x86_pvc_stable_mask = !pvc->vdso_force_unstable &&
pvc->stable_flag_supported ? PVCLOCK_FLAG_TSC_STABLE : 0;
bzero(vdso_th->th_res, sizeof(vdso_th->th_res));
return (pvc->cdev != NULL && amd_feature & AMDID_RDTSCP);
}
#endif
void
pvclock_gettime(struct pvclock *pvc, struct timespec *ts)
{
@ -238,9 +271,19 @@ void
pvclock_init(struct pvclock *pvc, device_t dev, const char *tc_name,
int tc_quality, u_int tc_flags)
{
struct make_dev_args mda;
int err;
KASSERT(((uintptr_t)pvc->timeinfos & PAGE_MASK) == 0,
("Specified time info page(s) address is not page-aligned."));
/* Set up vDSO stable-flag suppression test facility: */
pvc->vdso_force_unstable = false;
SYSCTL_ADD_BOOL(device_get_sysctl_ctx(dev),
SYSCTL_CHILDREN(device_get_sysctl_tree(dev)), OID_AUTO,
"vdso_force_unstable", CTLFLAG_RW, &pvc->vdso_force_unstable, 0,
"Forcibly deassert stable flag in vDSO codepath");
/* Set up timecounter and timecounter-supporting members: */
pvc->tc.tc_get_timecount = pvclock_tc_get_timecount;
pvc->tc.tc_poll_pps = NULL;
@ -250,11 +293,27 @@ pvclock_init(struct pvclock *pvc, device_t dev, const char *tc_name,
pvc->tc.tc_quality = tc_quality;
pvc->tc.tc_flags = tc_flags;
pvc->tc.tc_priv = pvc;
pvc->tc.tc_fill_vdso_timehands = NULL;
pvc->tc.tc_fill_vdso_timehands = pvclock_tc_vdso_timehands;
#ifdef COMPAT_FREEBSD32
pvc->tc.tc_fill_vdso_timehands32 = NULL;
pvc->tc.tc_fill_vdso_timehands32 = pvclock_tc_vdso_timehands32;
#endif
/* Set up cdev for userspace mmapping of vCPU 0 time info page: */
make_dev_args_init(&mda);
mda.mda_devsw = &pvclock_cdev_cdevsw;
mda.mda_uid = UID_ROOT;
mda.mda_gid = GID_WHEEL;
mda.mda_mode = 0444;
mda.mda_si_drv1 = pvc->timeinfos;
err = make_dev_s(&mda, &pvc->cdev, PVCLOCK_CDEVNAME);
if (err != 0) {
device_printf(dev, "Could not create /dev/%s, error %d. Fast "
"time of day will be unavailable for this timecounter.\n",
PVCLOCK_CDEVNAME, err);
KASSERT(pvc->cdev == NULL,
("Failed make_dev_s() unexpectedly inited cdev."));
}
/* Register timecounter: */
tc_init(&pvc->tc);

4
sys/x86/x86/tsc.c
View File

@ -870,6 +870,8 @@ x86_tsc_vdso_timehands(struct vdso_timehands *vdso_th, struct timecounter *tc)
vdso_th->th_algo = VDSO_TH_ALGO_X86_TSC;
vdso_th->th_x86_shift = (int)(intptr_t)tc->tc_priv;
vdso_th->th_x86_hpet_idx = 0xffffffff;
vdso_th->th_x86_pvc_last_systime = 0;
vdso_th->th_x86_pvc_stable_mask = 0;
bzero(vdso_th->th_res, sizeof(vdso_th->th_res));
return (1);
}
@ -883,6 +885,8 @@ x86_tsc_vdso_timehands32(struct vdso_timehands32 *vdso_th32,
vdso_th32->th_algo = VDSO_TH_ALGO_X86_TSC;
vdso_th32->th_x86_shift = (int)(intptr_t)tc->tc_priv;
vdso_th32->th_x86_hpet_idx = 0xffffffff;
vdso_th32->th_x86_pvc_last_systime = 0;
vdso_th32->th_x86_pvc_stable_mask = 0;
bzero(vdso_th32->th_res, sizeof(vdso_th32->th_res));
return (1);
}