If the hypervisor supports MSR based access to the APIC registers
(EOI, TPR and ICR), implement the MSR based access.
Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
---
arch/x86/include/uapi/asm/hyperv.h | 5 +++
arch/x86/kernel/cpu/mshyperv.c | 69 ++++++++++++++++++++++++++++++++++++
2 files changed, 74 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index 90c458e..6ce69e0 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -140,6 +140,11 @@
*/
#define HV_X64_RELAXED_TIMING_RECOMMENDED (1 << 5)
+/*
+ * Recommend using x2APIC MSRs.
+ */
+#define HV_X64_X2APIC_MSRS_RECOMMENDED (1 << 8)
+
/* MSR used to identify the guest OS. */
#define HV_X64_MSR_GUEST_OS_ID 0x40000000
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 939155f..dd2eb49 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -110,6 +110,55 @@ static struct clocksource hyperv_cs = {
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
+static u64 ms_hv_apic_icr_read(void)
+{
+ u64 reg_val;
+
+ rdmsrl(HV_X64_MSR_ICR, reg_val);
+ return reg_val;
+}
+
+static void ms_hv_apic_icr_write(u32 low, u32 id)
+{
+ u64 reg_val;
+
+ reg_val = SET_APIC_DEST_FIELD(id);
+ reg_val = (reg_val << 32);
+ reg_val |= low;
+
+ wrmsrl(HV_X64_MSR_EOI, reg_val);
+}
+
+static u32 ms_hv_apic_read(u32 reg)
+{
+ u64 reg_val;
+
+ switch (reg) {
+ case APIC_EOI:
+ case APIC_TASKPRI:
+ rdmsrl(HV_X64_MSR_EOI, reg_val);
+ return reg_val;
+
+ default:
+ return native_apic_mem_read(reg);
+ }
+}
+
+static void ms_hv_apic_write(u32 reg, u32 val)
+{
+ u64 reg_val;
+
+ reg_val = val;
+ switch (reg) {
+ case APIC_EOI:
+ case APIC_TASKPRI:
+ wrmsrl(HV_X64_MSR_EOI, reg_val);
+ default:
+ native_apic_mem_write(reg, val);
+ }
+}
+
+
static void __init ms_hyperv_init_platform(void)
{
/*
@@ -143,11 +192,31 @@ static void __init ms_hyperv_init_platform(void)
no_timer_check = 1;
#endif
+ if (ms_hyperv.features & HV_X64_MSR_APIC_ACCESS_AVAILABLE) {
+ /*
+ * Setup the hooks for optimized APIC read/write.
+ */
+ apic->read = ms_hv_apic_read;
+ apic->write = ms_hv_apic_write;
+ apic->icr_write = ms_hv_apic_icr_write;
+ apic->icr_read = ms_hv_apic_icr_read;
+ apic->eoi_write = ms_hv_apic_write;
+ }
+
+}
+
+static bool ms_hyperv_x2apic(void)
+{
+ if (ms_hyperv.hints & HV_X64_X2APIC_MSRS_RECOMMENDED)
+ return true;
+ else
+ return false;
}
const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
.name = "Microsoft HyperV",
.detect = ms_hyperv_platform,
.init_platform = ms_hyperv_init_platform,
+ .x2apic_available = ms_hyperv_x2apic
};
EXPORT_SYMBOL(x86_hyper_ms_hyperv);
--
1.7.4.1
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