[Xen-devel] [PATCH v5 08/12] x86/hyperv: provide Hyper-V hypercall functions

[Wei Liu <wl@xen.org>]

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

Signed-off-by: Wei Liu <liuwe@microsoft.com>
---
v5:
1. Switch back to direct call
2. Fix some issues pointed out by Jan

I tried using the asm(".equ ..") trick but hit a problem with %c again.

mm.c:5736:5: error: invalid 'asm': operand is not a condition code, invalid operand code 'c'
               asm ( ".equ HV_HCALL_PAGE, %c0; .global HV_HCALL_PAGE"
---
 MAINTAINERS                              |  1 +
 xen/arch/x86/guest/hyperv/hyperv.c       |  6 ++
 xen/arch/x86/xen.lds.S                   |  4 +
 xen/include/asm-x86/fixmap.h             |  3 +-
 xen/include/asm-x86/guest/hyperv-hcall.h | 96 ++++++++++++++++++++++++
 5 files changed, 108 insertions(+), 2 deletions(-)
 create mode 100644 xen/include/asm-x86/guest/hyperv-hcall.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 04d91482cd..d0a5ed635b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -519,6 +519,7 @@ S:	Supported
 F:	xen/arch/x86/guest/hyperv/
 F:	xen/arch/x86/hvm/viridian/
 F:	xen/include/asm-x86/guest/hyperv.h
+F:	xen/include/asm-x86/guest/hyperv-hcall.h
 F:	xen/include/asm-x86/guest/hyperv-tlfs.h
 F:	xen/include/asm-x86/hvm/viridian.h
 
diff --git a/xen/arch/x86/guest/hyperv/hyperv.c b/xen/arch/x86/guest/hyperv/hyperv.c
index 2bedcc438c..932a648ff7 100644
--- a/xen/arch/x86/guest/hyperv/hyperv.c
+++ b/xen/arch/x86/guest/hyperv/hyperv.c
@@ -123,6 +123,12 @@ static const struct hypervisor_ops ops = {
     .setup = setup,
 };
 
+static void __maybe_unused build_assertions(void)
+{
+    /* We use 1 in linker script */
+    BUILD_BUG_ON(FIX_X_HYPERV_HCALL != 1);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 97f9c07891..8e02b4c648 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -329,6 +329,10 @@ SECTIONS
   efi = .;
 #endif
 
+#ifdef CONFIG_HYPERV_GUEST
+  hv_hcall_page = ABSOLUTE(__fix_x_to_virt(1));
+#endif
+
   /* Sections to be discarded */
   /DISCARD/ : {
        *(.exit.text)
diff --git a/xen/include/asm-x86/fixmap.h b/xen/include/asm-x86/fixmap.h
index 8094546b75..a9bcb068cb 100644
--- a/xen/include/asm-x86/fixmap.h
+++ b/xen/include/asm-x86/fixmap.h
@@ -16,6 +16,7 @@
 
 #define FIXADDR_TOP (VMAP_VIRT_END - PAGE_SIZE)
 #define FIXADDR_X_TOP (XEN_VIRT_END - PAGE_SIZE)
+#define __fix_x_to_virt(x) (FIXADDR_X_TOP - ((x) << PAGE_SHIFT))
 
 #ifndef __ASSEMBLY__
 
@@ -110,8 +111,6 @@ extern void __set_fixmap_x(
 
 #define clear_fixmap_x(idx) __set_fixmap_x(idx, 0, 0)
 
-#define __fix_x_to_virt(x) (FIXADDR_X_TOP - ((x) << PAGE_SHIFT))
-
 #define fix_x_to_virt(x)   ((void *)__fix_x_to_virt(x))
 
 #endif /* __ASSEMBLY__ */
diff --git a/xen/include/asm-x86/guest/hyperv-hcall.h b/xen/include/asm-x86/guest/hyperv-hcall.h
new file mode 100644
index 0000000000..5b7509b3b5
--- /dev/null
+++ b/xen/include/asm-x86/guest/hyperv-hcall.h
@@ -0,0 +1,96 @@
+/******************************************************************************
+ * asm-x86/guest/hyperv-hcall.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_HCALL_H__
+#define __X86_HYPERV_HCALL_H__
+
+#include <xen/lib.h>
+#include <xen/types.h>
+
+#include <asm/asm_defns.h>
+#include <asm/fixmap.h>
+#include <asm/guest/hyperv-tlfs.h>
+#include <asm/page.h>
+
+static inline uint64_t hv_do_hypercall(uint64_t control, paddr_t input_addr,
+                                       paddr_t output_addr)
+{
+    uint64_t status;
+    register unsigned long r8 asm("r8") = output_addr;
+
+    asm volatile ( "call hv_hcall_page"
+                   : "=a" (status), "+c" (control),
+                     "+d" (input_addr) ASM_CALL_CONSTRAINT
+                   : "r" (r8)
+                   : "memory" );
+
+    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 = code | HV_HYPERCALL_FAST_BIT;
+    register unsigned long r8 asm("r8") = input2;
+
+    asm volatile ( "call hv_hcall_page"
+                   : "=a" (status), "+c" (control),
+                     "+d" (input1) ASM_CALL_CONSTRAINT
+                   : "r" (r8)
+                   : );
+
+    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 = MASK_EXTR(status, HV_HYPERCALL_REP_COMP_MASK);
+
+        control &= ~HV_HYPERCALL_REP_START_MASK;
+        control |= MASK_INSR(rep_comp, HV_HYPERCALL_REP_START_MASK);
+    } while ( rep_comp < rep_count );
+
+    return status;
+}
+
+#endif /* __X86_HYPERV_HCALL_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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