[Xen-devel] [PATCH v7 06/10] 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>
Reviewed-by: Paul Durrant <pdurrant@amazon.com>
---
v7:
1. Use ASM_CONSTANT and put it in hyperv.c

v6:
1. Use asm(...) to generate symbol
2. Add a comment regarding volatile registers

v5:
1. Switch back to direct call
2. Fix some issues pointed out by Jan
---
 MAINTAINERS                              |  1 +
 xen/arch/x86/guest/hyperv/hyperv.c       |  2 +
 xen/arch/x86/xen.lds.S                   |  4 +
 xen/include/asm-x86/guest/hyperv-hcall.h | 97 ++++++++++++++++++++++++
 4 files changed, 104 insertions(+)
 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 2e20a96f30..888bda25b0 100644
--- a/xen/arch/x86/guest/hyperv/hyperv.c
+++ b/xen/arch/x86/guest/hyperv/hyperv.c
@@ -118,6 +118,8 @@ static void __init setup_hypercall_page(void)
 
 static void __init setup(void)
 {
+    ASM_CONSTANT(HV_HCALL_PAGE, __fix_x_to_virt(FIX_X_HYPERV_HCALL));
+
     setup_hypercall_page();
 }
 
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 44fda616d5..7f9459d683 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -326,6 +326,10 @@ SECTIONS
   efi = .;
 #endif
 
+#ifdef CONFIG_HYPERV_GUEST
+  hv_hcall_page = ABSOLUTE(HV_HCALL_PAGE);
+#endif
+
   /* Sections to be discarded */
   /DISCARD/ : {
        *(.exit.text)
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..4d3b131b3a
--- /dev/null
+++ b/xen/include/asm-x86/guest/hyperv-hcall.h
@@ -0,0 +1,97 @@
+/******************************************************************************
+ * 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;
+
+    /* See TLFS for volatile registers */
+    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;
+
+    /* See TLFS for volatile registers */
+    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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