diff mbox series

[v6,06/11] x86/hyperv: provide Hyper-V hypercall functions

Message ID 20200131174930.31045-7-liuwe@microsoft.com (mailing list archive)
State Superseded
Headers show
Series More Hyper-V infrastructures | expand

Commit Message

Wei Liu Jan. 31, 2020, 5:49 p.m. UTC 
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>
---
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/mm.c                        |  4 +-
 xen/arch/x86/xen.lds.S                   |  4 +
 xen/include/asm-x86/guest/hyperv-hcall.h | 97 ++++++++++++++++++++++++
 4 files changed, 105 insertions(+), 1 deletion(-)
 create mode 100644 xen/include/asm-x86/guest/hyperv-hcall.h

Comments

Jan Beulich Feb. 3, 2020, 1:26 p.m. UTC | #1 
On 31.01.2020 18:49, Wei Liu wrote:
> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -375,9 +375,11 @@ void __init arch_init_memory(void)
>      }
>  #endif
>  
> -    /* Generate a symbol to be used in linker script */
> +    /* Generate symbols to be used in linker script */
>      asm ( ".equ FIXADDR_X_SIZE, %P0; .global FIXADDR_X_SIZE"
>            :: "i" (FIXADDR_X_SIZE) );
> +    asm ( ".equ HV_HCALL_PAGE, %P0; .global HV_HCALL_PAGE"
> +          :: "i" (__fix_x_to_virt(FIX_X_HYPERV_HCALL)) );

Would this even build without CONFIG_HYPERV_GUEST? In any event
it doesn't belong here, but should go in a Hyper-V specific
file.

Seeing you now need two of these, how about macro-izing the
construct?

Jan
Wei Liu Feb. 3, 2020, 1:31 p.m. UTC | #2 
On Mon, Feb 03, 2020 at 02:26:24PM +0100, Jan Beulich wrote:
> On 31.01.2020 18:49, Wei Liu wrote:
> > --- a/xen/arch/x86/mm.c
> > +++ b/xen/arch/x86/mm.c
> > @@ -375,9 +375,11 @@ void __init arch_init_memory(void)
> >      }
> >  #endif
> >  
> > -    /* Generate a symbol to be used in linker script */
> > +    /* Generate symbols to be used in linker script */
> >      asm ( ".equ FIXADDR_X_SIZE, %P0; .global FIXADDR_X_SIZE"
> >            :: "i" (FIXADDR_X_SIZE) );
> > +    asm ( ".equ HV_HCALL_PAGE, %P0; .global HV_HCALL_PAGE"
> > +          :: "i" (__fix_x_to_virt(FIX_X_HYPERV_HCALL)) );
> 
> Would this even build without CONFIG_HYPERV_GUEST? In any event
> it doesn't belong here, but should go in a Hyper-V specific
> file.
> 

Good catch. When I did my full build tests it was done with my previous
version.

I can move this to hyperv.c.

> Seeing you now need two of these, how about macro-izing the
> construct?

What name would you suggest? I'm thinking about GEN_XEN_LDS_SYMBOL.

And presumably I should put it in xen/lib.h?

Wei.

> 
> Jan
Jan Beulich Feb. 3, 2020, 1:48 p.m. UTC | #3 
On 03.02.2020 14:31, Wei Liu wrote:
> On Mon, Feb 03, 2020 at 02:26:24PM +0100, Jan Beulich wrote:
>> On 31.01.2020 18:49, Wei Liu wrote:
>>> --- a/xen/arch/x86/mm.c
>>> +++ b/xen/arch/x86/mm.c
>>> @@ -375,9 +375,11 @@ void __init arch_init_memory(void)
>>>      }
>>>  #endif
>>>  
>>> -    /* Generate a symbol to be used in linker script */
>>> +    /* Generate symbols to be used in linker script */
>>>      asm ( ".equ FIXADDR_X_SIZE, %P0; .global FIXADDR_X_SIZE"
>>>            :: "i" (FIXADDR_X_SIZE) );
>>> +    asm ( ".equ HV_HCALL_PAGE, %P0; .global HV_HCALL_PAGE"
>>> +          :: "i" (__fix_x_to_virt(FIX_X_HYPERV_HCALL)) );
>>
>> Would this even build without CONFIG_HYPERV_GUEST? In any event
>> it doesn't belong here, but should go in a Hyper-V specific
>> file.
>>
> 
> Good catch. When I did my full build tests it was done with my previous
> version.
> 
> I can move this to hyperv.c.
> 
>> Seeing you now need two of these, how about macro-izing the
>> construct?
> 
> What name would you suggest? I'm thinking about GEN_XEN_LDS_SYMBOL.

In principle this isn't limiting things to use by xen.lds, so
I'd prefer to not encode such in the name. asm_constant()? Or
all caps if so preferred by others?

> And presumably I should put it in xen/lib.h?

Would be nice to have it there, but I'm afraid this is against
what gcc documents. Hence if anything the P would need to be
abstracted away as a per-arch thing. If you don't want to go
this far, asm_defns.h might be the best fit among the x86
headers.

Jan
Wei Liu Feb. 3, 2020, 1:51 p.m. UTC | #4 
On Mon, Feb 03, 2020 at 02:48:42PM +0100, Jan Beulich wrote:
> On 03.02.2020 14:31, Wei Liu wrote:
> > On Mon, Feb 03, 2020 at 02:26:24PM +0100, Jan Beulich wrote:
> >> On 31.01.2020 18:49, Wei Liu wrote:
> >>> --- a/xen/arch/x86/mm.c
> >>> +++ b/xen/arch/x86/mm.c
> >>> @@ -375,9 +375,11 @@ void __init arch_init_memory(void)
> >>>      }
> >>>  #endif
> >>>  
> >>> -    /* Generate a symbol to be used in linker script */
> >>> +    /* Generate symbols to be used in linker script */
> >>>      asm ( ".equ FIXADDR_X_SIZE, %P0; .global FIXADDR_X_SIZE"
> >>>            :: "i" (FIXADDR_X_SIZE) );
> >>> +    asm ( ".equ HV_HCALL_PAGE, %P0; .global HV_HCALL_PAGE"
> >>> +          :: "i" (__fix_x_to_virt(FIX_X_HYPERV_HCALL)) );
> >>
> >> Would this even build without CONFIG_HYPERV_GUEST? In any event
> >> it doesn't belong here, but should go in a Hyper-V specific
> >> file.
> >>
> > 
> > Good catch. When I did my full build tests it was done with my previous
> > version.
> > 
> > I can move this to hyperv.c.
> > 
> >> Seeing you now need two of these, how about macro-izing the
> >> construct?
> > 
> > What name would you suggest? I'm thinking about GEN_XEN_LDS_SYMBOL.
> 
> In principle this isn't limiting things to use by xen.lds, so
> I'd prefer to not encode such in the name. asm_constant()? Or
> all caps if so preferred by others?

I am certainly okay with ASM_CONSTANT().

> 
> > And presumably I should put it in xen/lib.h?
> 
> Would be nice to have it there, but I'm afraid this is against
> what gcc documents. Hence if anything the P would need to be
> abstracted away as a per-arch thing. If you don't want to go
> this far, asm_defns.h might be the best fit among the x86
> headers.

OK. asm_defns.h it is. Arm doesn't need this for now anyway.

Wei.

> 
> Jan
diff mbox series

Patch

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/mm.c b/xen/arch/x86/mm.c
index 6b1361845c..e7787c8fde 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -375,9 +375,11 @@  void __init arch_init_memory(void)
     }
 #endif
 
-    /* Generate a symbol to be used in linker script */
+    /* Generate symbols to be used in linker script */
     asm ( ".equ FIXADDR_X_SIZE, %P0; .global FIXADDR_X_SIZE"
           :: "i" (FIXADDR_X_SIZE) );
+    asm ( ".equ HV_HCALL_PAGE, %P0; .global HV_HCALL_PAGE"
+          :: "i" (__fix_x_to_virt(FIX_X_HYPERV_HCALL)) );
 }
 
 int page_is_ram_type(unsigned long mfn, unsigned long mem_type)
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index de0856b88e..ec8ab2bec6 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -328,6 +328,10 @@  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:
+ */