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authorKonrad Rzeszutek Wilk2012-02-13 22:26:32 -0500
committerKonrad Rzeszutek Wilk2012-03-10 12:44:44 -0500
commit73c154c60be106b47f15d1111fc2d75cc7a436f2 (patch)
treeaf32a6e0fd49bfafa1499cd1a8cdf15caae27054 /arch/x86/xen
parentcc7335b2f6acc0f24c7fac80ce536301f7d52214 (diff)
xen/enlighten: Expose MWAIT and MWAIT_LEAF if hypervisor OKs it.
For the hypervisor to take advantage of the MWAIT support it needs to extract from the ACPI _CST the register address. But the hypervisor does not have the support to parse DSDT so it relies on the initial domain (dom0) to parse the ACPI Power Management information and push it up to the hypervisor. The pushing of the data is done by the processor_harveset_xen module which parses the information that the ACPI parser has graciously exposed in 'struct acpi_processor'. For the ACPI parser to also expose the Cx states for MWAIT, we need to expose the MWAIT capability (leaf 1). Furthermore we also need to expose the MWAIT_LEAF capability (leaf 5) for cstate.c to properly function. The hypervisor could expose these flags when it traps the XEN_EMULATE_PREFIX operations, but it can't do it since it needs to be backwards compatible. Instead we choose to use the native CPUID to figure out if the MWAIT capability exists and use the XEN_SET_PDC query hypercall to figure out if the hypervisor wants us to expose the MWAIT_LEAF capability or not. Note: The XEN_SET_PDC query was implemented in c/s 23783: "ACPI: add _PDC input override mechanism". With this in place, instead of C3 ACPI IOPORT 415 we get now C3:ACPI FFH INTEL MWAIT 0x20 Note: The cpu_idle which would be calling the mwait variants for idling never gets set b/c we set the default pm_idle to be the hypercall variant. Acked-by: Jan Beulich <JBeulich@suse.com> [v2: Fix missing header file include and #ifdef] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'arch/x86/xen')
-rw-r--r--arch/x86/xen/enlighten.c93
1 files changed, 92 insertions, 1 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 312c9e3cb635..fe06bf4ef0e3 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -62,6 +62,15 @@
#include <asm/reboot.h>
#include <asm/stackprotector.h>
#include <asm/hypervisor.h>
+#include <asm/mwait.h>
+
+#ifdef CONFIG_ACPI
+#include <linux/acpi.h>
+#include <asm/acpi.h>
+#include <acpi/pdc_intel.h>
+#include <acpi/processor.h>
+#include <xen/interface/platform.h>
+#endif
#include "xen-ops.h"
#include "mmu.h"
@@ -200,13 +209,17 @@ static void __init xen_banner(void)
static __read_mostly unsigned int cpuid_leaf1_edx_mask = ~0;
static __read_mostly unsigned int cpuid_leaf1_ecx_mask = ~0;
+static __read_mostly unsigned int cpuid_leaf1_ecx_set_mask;
+static __read_mostly unsigned int cpuid_leaf5_ecx_val;
+static __read_mostly unsigned int cpuid_leaf5_edx_val;
+
static void xen_cpuid(unsigned int *ax, unsigned int *bx,
unsigned int *cx, unsigned int *dx)
{
unsigned maskebx = ~0;
unsigned maskecx = ~0;
unsigned maskedx = ~0;
-
+ unsigned setecx = 0;
/*
* Mask out inconvenient features, to try and disable as many
* unsupported kernel subsystems as possible.
@@ -214,9 +227,18 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
switch (*ax) {
case 1:
maskecx = cpuid_leaf1_ecx_mask;
+ setecx = cpuid_leaf1_ecx_set_mask;
maskedx = cpuid_leaf1_edx_mask;
break;
+ case CPUID_MWAIT_LEAF:
+ /* Synthesize the values.. */
+ *ax = 0;
+ *bx = 0;
+ *cx = cpuid_leaf5_ecx_val;
+ *dx = cpuid_leaf5_edx_val;
+ return;
+
case 0xb:
/* Suppress extended topology stuff */
maskebx = 0;
@@ -232,9 +254,75 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
*bx &= maskebx;
*cx &= maskecx;
+ *cx |= setecx;
*dx &= maskedx;
+
}
+static bool __init xen_check_mwait(void)
+{
+#ifdef CONFIG_ACPI
+ struct xen_platform_op op = {
+ .cmd = XENPF_set_processor_pminfo,
+ .u.set_pminfo.id = -1,
+ .u.set_pminfo.type = XEN_PM_PDC,
+ };
+ uint32_t buf[3];
+ unsigned int ax, bx, cx, dx;
+ unsigned int mwait_mask;
+
+ /* We need to determine whether it is OK to expose the MWAIT
+ * capability to the kernel to harvest deeper than C3 states from ACPI
+ * _CST using the processor_harvest_xen.c module. For this to work, we
+ * need to gather the MWAIT_LEAF values (which the cstate.c code
+ * checks against). The hypervisor won't expose the MWAIT flag because
+ * it would break backwards compatibility; so we will find out directly
+ * from the hardware and hypercall.
+ */
+ if (!xen_initial_domain())
+ return false;
+
+ ax = 1;
+ cx = 0;
+
+ native_cpuid(&ax, &bx, &cx, &dx);
+
+ mwait_mask = (1 << (X86_FEATURE_EST % 32)) |
+ (1 << (X86_FEATURE_MWAIT % 32));
+
+ if ((cx & mwait_mask) != mwait_mask)
+ return false;
+
+ /* We need to emulate the MWAIT_LEAF and for that we need both
+ * ecx and edx. The hypercall provides only partial information.
+ */
+
+ ax = CPUID_MWAIT_LEAF;
+ bx = 0;
+ cx = 0;
+ dx = 0;
+
+ native_cpuid(&ax, &bx, &cx, &dx);
+
+ /* Ask the Hypervisor whether to clear ACPI_PDC_C_C2C3_FFH. If so,
+ * don't expose MWAIT_LEAF and let ACPI pick the IOPORT version of C3.
+ */
+ buf[0] = ACPI_PDC_REVISION_ID;
+ buf[1] = 1;
+ buf[2] = (ACPI_PDC_C_CAPABILITY_SMP | ACPI_PDC_EST_CAPABILITY_SWSMP);
+
+ set_xen_guest_handle(op.u.set_pminfo.pdc, buf);
+
+ if ((HYPERVISOR_dom0_op(&op) == 0) &&
+ (buf[2] & (ACPI_PDC_C_C1_FFH | ACPI_PDC_C_C2C3_FFH))) {
+ cpuid_leaf5_ecx_val = cx;
+ cpuid_leaf5_edx_val = dx;
+ }
+ return true;
+#else
+ return false;
+#endif
+}
static void __init xen_init_cpuid_mask(void)
{
unsigned int ax, bx, cx, dx;
@@ -261,6 +349,9 @@ static void __init xen_init_cpuid_mask(void)
/* Xen will set CR4.OSXSAVE if supported and not disabled by force */
if ((cx & xsave_mask) != xsave_mask)
cpuid_leaf1_ecx_mask &= ~xsave_mask; /* disable XSAVE & OSXSAVE */
+
+ if (xen_check_mwait())
+ cpuid_leaf1_ecx_set_mask = (1 << (X86_FEATURE_MWAIT % 32));
}
static void xen_set_debugreg(int reg, unsigned long val)