⬢ DragonFlyBSD Kernel Audit
DF-5483 / estforce.c
← back to finding ↓ download raw 
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
/*
 * DF-5483 rig helper -- substitutes ONLY the missing CPUID advertisement.
 *
 * This QEMU build masks CPUID.01H.ECX.EST under both KVM and TCG (KVM lacks
 * the host bit; TCG masks est as unimplemented), so the Intel P-state md
 * probe (acpi_pst_intel_probe, acpi_pstate_machdep.c:418-428) would bail
 * and the driver would never engage -- exactly the DF-5155/DF-5160
 * "VMM lies about CPUID" premise, constructed here deliberately.
 *
 * The module sets cpu_feature2 |= CPUID2_EST from the boot loader
 * (estforce_load="YES"), i.e. BEFORE acpi0/cpu_pst probe.  Everything
 * afterwards is the genuine stock driver: parse _PSS/_PCT, allocate the
 * firmware-named IO ports, and write the _PSS control value at the first
 * P-state transition.
 */
#include <sys/param.h>
#include <sys/module.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <machine/cputypes.h>
#include <machine/specialreg.h>

static int
estforce_modevent(module_t mod, int type, void *data)
{
	switch (type) {
	case MOD_LOAD:
		if (cpu_vendor_id == CPU_VENDOR_INTEL &&
		    (cpu_feature2 & CPUID2_EST) == 0) {
			cpu_feature2 |= CPUID2_EST;
			kprintf("estforce: cpu_feature2 |= CPUID2_EST "
			    "(now %#x)\n", cpu_feature2);
		} else {
			kprintf("estforce: nothing to do "
			    "(vendor %d, f2 %#x)\n",
			    cpu_vendor_id, cpu_feature2);
		}
		return 0;
	case MOD_UNLOAD:
		return 0;
	}
	return EOPNOTSUPP;
}

static moduledata_t estforce_mod = {
	"estforce",
	estforce_modevent,
	NULL
};
DECLARE_MODULE(estforce, estforce_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
MODULE_VERSION(estforce, 1);