[Xen-devel] [PATCH 5/8] x86/hyperv: provide Hyper-V hypercall functions

[Wei Liu <wl@xxxxxxx>]

These functions will be used later to make hypercalls to Hyper-V.

I couldn't find reference in TLFS that Hyper-V clobbers flags and
r9-r11, but Linux's commit message says it does. Err on the safe side.

Signed-off-by: Wei Liu <liuwe@xxxxxxxxxxxxx>
---
 xen/include/asm-x86/guest/hyperv-hypercall.h | 105 +++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 xen/include/asm-x86/guest/hyperv-hypercall.h

diff --git a/xen/include/asm-x86/guest/hyperv-hypercall.h 
b/xen/include/asm-x86/guest/hyperv-hypercall.h
new file mode 100644
index 0000000000..6017123be5
--- /dev/null
+++ b/xen/include/asm-x86/guest/hyperv-hypercall.h
@@ -0,0 +1,105 @@
+/******************************************************************************
+ * asm-x86/guest/hyperv-hypercall.h
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms and conditions of the GNU General Public
+ * License, version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright (c) 2019 Microsoft.
+ */
+
+#ifndef __X86_HYPERV_HYPERCALL_H__
+#define __X86_HYPERV_HYPERCALL_H__
+
+#include <xen/types.h>
+
+#include <asm/asm_defns.h>
+#include <asm/guest/hyperv-tlfs.h>
+#include <asm/page.h>
+
+extern void *hv_hypercall;
+
+static inline uint64_t hv_do_hypercall(uint64_t control, paddr_t input, 
paddr_t output)
+{
+    uint64_t status;
+
+    if ( !hv_hypercall )
+        return ~0ULL;
+
+    asm volatile ("mov %[output], %%r8\n"
+                  "call *%[hypercall_page]"
+                  : "=a" (status), "+c" (control),
+                    "+d" (input) ASM_CALL_CONSTRAINT
+                  : [output] "rm" (output),
+                    [hypercall_page] "m" (hv_hypercall)
+                  : "cc", "memory", "r8", "r9", "r10", "r11");
+
+    return status;
+}
+
+static inline uint64_t hv_do_fast_hypercall(uint16_t code,
+                                            uint64_t input1, uint64_t input2)
+{
+    uint64_t status;
+    uint64_t control = (uint64_t)code | HV_HYPERCALL_FAST_BIT;
+
+    if ( !hv_hypercall )
+        return ~0ULL;
+
+    asm volatile ("mov %[input2], %%r8\n"
+                  "call *%[hypercall_page]"
+                  : "=a" (status), "+c" (control),
+                    "+d" (input1) ASM_CALL_CONSTRAINT
+                  : [input2] "rm" (input2),
+                    [hypercall_page] "m" (hv_hypercall)
+                  : "cc", "r8", "r9", "r10", "r11");
+
+    return status;
+}
+
+static inline uint64_t hv_do_rep_hypercall(uint16_t code, uint16_t rep_count,
+                                           uint16_t varhead_size,
+                                           paddr_t input, paddr_t output)
+{
+    uint64_t control = code;
+    uint64_t status;
+    uint16_t rep_comp;
+
+    control |= (uint64_t)varhead_size << HV_HYPERCALL_VARHEAD_OFFSET;
+    control |= (uint64_t)rep_count << HV_HYPERCALL_REP_COMP_OFFSET;
+
+    do {
+        status = hv_do_hypercall(control, input, output);
+        if ( (status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS )
+            break;
+
+        rep_comp = (status & HV_HYPERCALL_REP_COMP_MASK) >>
+            HV_HYPERCALL_REP_COMP_OFFSET;
+
+        control &= ~HV_HYPERCALL_REP_START_MASK;
+        control |= (uint64_t)rep_comp << HV_HYPERCALL_REP_COMP_OFFSET;
+
+    } while ( rep_comp < rep_count );
+
+    return status;
+}
+
+#endif /* __X86_HYPERV_HYPERCALL_H__ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
-- 
2.20.1


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