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[PATCH v6 06/10] x86/hyper-v: implement rep hypercalls

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Rep hypercalls are normal hypercalls which perform multiple actions at
once. Hyper-V guarantees to return exectution to the caller in not more
than 50us and the caller needs to use hypercall continuation. Touch NMI
watchdog between hypercall invocations.

This is going to be used for HvFlushVirtualAddressList hypercall for
remote TLB flushing.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
Changes since v5:
- Define Hyper-V hypercall input 'magic' [Andy Shevchenko]
---
 arch/x86/include/asm/mshyperv.h | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 03b5127..eca4f78 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -4,6 +4,7 @@
 #include <linux/types.h>
 #include <linux/interrupt.h>
 #include <linux/clocksource.h>
+#include <linux/nmi.h>
 #include <asm/hyperv.h>
 
 /*
@@ -212,7 +213,13 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 	return hv_status;
 }
 
+#define HV_HYPERCALL_RESULT_MASK	GENMASK_ULL(15, 0)
 #define HV_HYPERCALL_FAST_BIT		BIT(16)
+#define HV_HYPERCALL_VARHEAD_OFFSET	17
+#define HV_HYPERCALL_REP_COMP_OFFSET	32
+#define HV_HYPERCALL_REP_COMP_MASK	GENMASK_ULL(43, 32)
+#define HV_HYPERCALL_REP_START_OFFSET	48
+#define HV_HYPERCALL_REP_START_MASK	GENMASK_ULL(59, 48)
 
 /* Fast hypercall with 8 bytes of input and no output */
 static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
@@ -246,6 +253,38 @@ static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
 		return hv_status;
 }
 
+/*
+ * Rep hypercalls. Callers of this functions are supposed to ensure that
+ * rep_count and varhead_size comply with Hyper-V hypercall definition.
+ */
+static inline u64 hv_do_rep_hypercall(u16 code, u16 rep_count, u16 varhead_size,
+				      void *input, void *output)
+{
+	u64 control = code;
+	u64 status;
+	u16 rep_comp;
+
+	control |= (u64)varhead_size << HV_HYPERCALL_VARHEAD_OFFSET;
+	control |= (u64)rep_count << HV_HYPERCALL_REP_COMP_OFFSET;
+
+	do {
+		status = hv_do_hypercall(control, input, output);
+		if ((status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS)
+			return status;
+
+		/* Bits 32-43 of status have 'Reps completed' data. */
+		rep_comp = (status & HV_HYPERCALL_REP_COMP_MASK) >>
+			HV_HYPERCALL_REP_COMP_OFFSET;
+
+		control &= ~HV_HYPERCALL_REP_START_MASK;
+		control |= (u64)rep_comp << HV_HYPERCALL_REP_START_OFFSET;
+
+		touch_nmi_watchdog();
+	} while (rep_comp < rep_count);
+
+	return status;
+}
+
 void hyperv_init(void);
 void hyperv_report_panic(struct pt_regs *regs);
 bool hv_is_hypercall_page_setup(void);
-- 
2.9.4

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[PATCH v6 00/10] Hyper-V: praravirtualized remote TLB flushing and hypercall improvements Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-06-01 19:50 +0200
  [PATCH v6 10/10] tracing/hyper-v: trace hyperv_mmu_flush_tlb_others() Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-06-01 19:50 +0200
  [PATCH v6 06/10] x86/hyper-v: implement rep hypercalls Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-06-01 19:50 +0200
  [PATCH v6 08/10] x86/hyper-v: use hypercall for remote TLB flush Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-06-01 19:50 +0200
  [PATCH v6 07/10] hyper-v: globalize vp_index Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-06-01 19:50 +0200
  [PATCH v6 03/10] x86/hyper-v: make hv_do_hypercall() inline Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-06-01 20:00 +0200
  [PATCH v6 05/10] hyper-v: use fast hypercall for HVCALL_SIGNAL_EVENT Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-06-01 20:00 +0200

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