grub2/0131-calibrate_tsc-use-the-Stall-EFI-boot-service-on-GRUB.patch

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From 8d52adac75a53452e6b1e6ed527b90b7cbaac7a6 Mon Sep 17 00:00:00 2001
From: Laszlo Ersek <lersek@redhat.com>
Date: Fri, 10 Oct 2014 11:11:09 +0200
Subject: [PATCH 131/192] calibrate_tsc(): use the Stall() EFI boot service on
GRUB_MACHINE_EFI
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1150698
HyperV Gen2 virtual machines have no PIT; guest code should rely on UEFI
services instead.
Signed-off-by: RHEL Ninjas <example@example.com>
---
grub-core/kern/i386/tsc.c | 59 +++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 57 insertions(+), 2 deletions(-)
diff --git a/grub-core/kern/i386/tsc.c b/grub-core/kern/i386/tsc.c
index 2e85289d8..0787b6f3e 100644
--- a/grub-core/kern/i386/tsc.c
+++ b/grub-core/kern/i386/tsc.c
@@ -24,6 +24,17 @@
#include <grub/misc.h>
#include <grub/i386/tsc.h>
#include <grub/i386/cpuid.h>
+#ifdef GRUB_MACHINE_XEN
+# include <grub/xen.h>
+#else
+# ifdef GRUB_MACHINE_EFI
+# include <grub/efi/efi.h>
+# include <grub/efi/api.h>
+# else
+# include <grub/i386/pit.h>
+# endif
+#endif
+#include <grub/cpu/io.h>
/* This defines the value TSC had at the epoch (that is, when we calibrated it). */
static grub_uint64_t tsc_boot_time;
@@ -33,6 +44,44 @@ static grub_uint64_t tsc_boot_time;
in 32-bit. */
grub_uint32_t grub_tsc_rate;
+#ifndef GRUB_MACHINE_XEN
+
+static void
+grub_stall (grub_uint16_t tics)
+{
+# ifdef GRUB_MACHINE_EFI
+ grub_uint64_t microseconds;
+
+ microseconds = (grub_uint64_t)tics * 1000 * 1000 * 3 / 3579545;
+ efi_call_1 (grub_efi_system_table->boot_services->stall, microseconds);
+# else
+ /* Disable timer2 gate and speaker. */
+ grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT)
+ & ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2),
+ GRUB_PIT_SPEAKER_PORT);
+
+ /* Set tics. */
+ grub_outb (GRUB_PIT_CTRL_SELECT_2 | GRUB_PIT_CTRL_READLOAD_WORD,
+ GRUB_PIT_CTRL);
+ grub_outb (tics & 0xff, GRUB_PIT_COUNTER_2);
+ grub_outb (tics >> 8, GRUB_PIT_COUNTER_2);
+
+ /* Enable timer2 gate, keep speaker disabled. */
+ grub_outb ((grub_inb (GRUB_PIT_SPEAKER_PORT) & ~ GRUB_PIT_SPK_DATA)
+ | GRUB_PIT_SPK_TMR2,
+ GRUB_PIT_SPEAKER_PORT);
+
+ /* Wait. */
+ while ((grub_inb (GRUB_PIT_SPEAKER_PORT) & GRUB_PIT_SPK_TMR2_LATCH) == 0x00);
+
+ /* Disable timer2 gate and speaker. */
+ grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT)
+ & ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2),
+ GRUB_PIT_SPEAKER_PORT);
+# endif
+}
+#endif
+
static grub_uint64_t
grub_tsc_get_time_ms (void)
{
@@ -46,8 +95,14 @@ grub_tsc_get_time_ms (void)
static int
calibrate_tsc_hardcode (void)
{
- grub_tsc_rate = 5368;/* 800 MHz */
- return 1;
+ /* First calibrate the TSC rate (relative, not absolute time). */
+ grub_uint64_t end_tsc;
+
+ tsc_boot_time = grub_get_tsc ();
+ grub_stall (0xffff);
+ end_tsc = grub_get_tsc ();
+
+ grub_tsc_rate = grub_divmod64 ((55ULL << 32), end_tsc - tsc_boot_time, 0);
}
void
--
2.13.4