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Subject[RFC PATCH 03/16] x86/xen: make hypercall_page generic
Date
Make hypercall_page a generic interface which can be implemented
by other hypervisors. With this change, hypercall_page now points to
the newly introduced xen_hypercall_page which is seeded by Xen, or
to one that is filled in by a different hypervisor.

Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
---
arch/x86/include/asm/xen/hypercall.h | 12 +++++++-----
arch/x86/xen/enlighten.c | 1 +
arch/x86/xen/enlighten_hvm.c | 3 ++-
arch/x86/xen/enlighten_pv.c | 1 +
arch/x86/xen/enlighten_pvh.c | 3 ++-
arch/x86/xen/xen-asm_32.S | 2 +-
arch/x86/xen/xen-asm_64.S | 2 +-
arch/x86/xen/xen-head.S | 8 ++++----
8 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h
index ef05bea7010d..1a3cd6680e6f 100644
--- a/arch/x86/include/asm/xen/hypercall.h
+++ b/arch/x86/include/asm/xen/hypercall.h
@@ -86,11 +86,13 @@ struct xen_dm_op_buf;
* there aren't more than 5 arguments...)
*/

-extern struct { char _entry[32]; } hypercall_page[];
+struct hypercall_entry { char _entry[32]; };
+extern struct hypercall_entry xen_hypercall_page[128];
+extern struct hypercall_entry *hypercall_page;

-#define __HYPERCALL "call hypercall_page+%c[offset]"
+#define __HYPERCALL CALL_NOSPEC
#define __HYPERCALL_ENTRY(x) \
- [offset] "i" (__HYPERVISOR_##x * sizeof(hypercall_page[0]))
+ [thunk_target] "0" (hypercall_page + __HYPERVISOR_##x)

#ifdef CONFIG_X86_32
#define __HYPERCALL_RETREG "eax"
@@ -116,7 +118,7 @@ extern struct { char _entry[32]; } hypercall_page[];
register unsigned long __arg4 asm(__HYPERCALL_ARG4REG) = __arg4; \
register unsigned long __arg5 asm(__HYPERCALL_ARG5REG) = __arg5;

-#define __HYPERCALL_0PARAM "=r" (__res), ASM_CALL_CONSTRAINT
+#define __HYPERCALL_0PARAM "=&r" (__res), ASM_CALL_CONSTRAINT
#define __HYPERCALL_1PARAM __HYPERCALL_0PARAM, "+r" (__arg1)
#define __HYPERCALL_2PARAM __HYPERCALL_1PARAM, "+r" (__arg2)
#define __HYPERCALL_3PARAM __HYPERCALL_2PARAM, "+r" (__arg3)
@@ -208,7 +210,7 @@ xen_single_call(unsigned int call,

asm volatile(CALL_NOSPEC
: __HYPERCALL_5PARAM
- : [thunk_target] "a" (&hypercall_page[call])
+ : [thunk_target] "0" (hypercall_page + call)
: __HYPERCALL_CLOBBER5);

return (long)__res;
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 750f46ad018a..e9dc92e79afa 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -20,6 +20,7 @@
#include "smp.h"
#include "pmu.h"

+struct hypercall_entry *hypercall_page;
EXPORT_SYMBOL_GPL(hypercall_page);

/*
diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index ffc5791675b2..4d85cd2ff261 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -115,8 +115,9 @@ static void __init init_hvm_pv_info(void)

pv_info.name = "Xen HVM";
msr = cpuid_ebx(base + 2);
- pfn = __pa(hypercall_page);
+ pfn = __pa(xen_hypercall_page);
wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32));
+ hypercall_page = xen_hypercall_page;
}

xen_setup_features();
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index a4e04b0cc596..3239e8452ede 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1217,6 +1217,7 @@ asmlinkage __visible void __init xen_start_kernel(void)

if (!xen_start_info)
return;
+ hypercall_page = xen_hypercall_page;

xenhost_register(xenhost_r1, &xh_pv_ops);

diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.c
index c07eba169572..e47866fcb7ea 100644
--- a/arch/x86/xen/enlighten_pvh.c
+++ b/arch/x86/xen/enlighten_pvh.c
@@ -46,8 +46,9 @@ void __init xen_pvh_init(void)
xen_start_flags = pvh_start_info.flags;

msr = cpuid_ebx(xen_cpuid_base() + 2);
- pfn = __pa(hypercall_page);
+ pfn = __pa(xen_hypercall_page);
wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32));
+ hypercall_page = xen_hypercall_page;
}

void __init mem_map_via_hcall(struct boot_params *boot_params_p)
diff --git a/arch/x86/xen/xen-asm_32.S b/arch/x86/xen/xen-asm_32.S
index c15db060a242..ee4998055ea9 100644
--- a/arch/x86/xen/xen-asm_32.S
+++ b/arch/x86/xen/xen-asm_32.S
@@ -121,7 +121,7 @@ xen_iret_end_crit:

hyper_iret:
/* put this out of line since its very rarely used */
- jmp hypercall_page + __HYPERVISOR_iret * 32
+ jmp xen_hypercall_page + __HYPERVISOR_iret * 32

.globl xen_iret_start_crit, xen_iret_end_crit

diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
index 1e9ef0ba30a5..2172d6aec9a3 100644
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -70,7 +70,7 @@ ENTRY(xen_early_idt_handler_array)
END(xen_early_idt_handler_array)
__FINIT

-hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32
+hypercall_iret = xen_hypercall_page + __HYPERVISOR_iret * 32
/*
* Xen64 iret frame:
*
diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index 5077ead5e59c..7ff5437bd83f 100644
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -58,18 +58,18 @@ END(startup_xen)

.pushsection .text
.balign PAGE_SIZE
-ENTRY(hypercall_page)
+ENTRY(xen_hypercall_page)
.rept (PAGE_SIZE / 32)
UNWIND_HINT_EMPTY
.skip 32
.endr

#define HYPERCALL(n) \
- .equ xen_hypercall_##n, hypercall_page + __HYPERVISOR_##n * 32; \
+ .equ xen_hypercall_##n, xen_hypercall_page + __HYPERVISOR_##n * 32; \
.type xen_hypercall_##n, @function; .size xen_hypercall_##n, 32
#include <asm/xen-hypercalls.h>
#undef HYPERCALL
-END(hypercall_page)
+END(xen_hypercall_page)
.popsection

ELFNOTE(Xen, XEN_ELFNOTE_GUEST_OS, .asciz "linux")
@@ -85,7 +85,7 @@ END(hypercall_page)
#ifdef CONFIG_XEN_PV
ELFNOTE(Xen, XEN_ELFNOTE_ENTRY, _ASM_PTR startup_xen)
#endif
- ELFNOTE(Xen, XEN_ELFNOTE_HYPERCALL_PAGE, _ASM_PTR hypercall_page)
+ ELFNOTE(Xen, XEN_ELFNOTE_HYPERCALL_PAGE, _ASM_PTR xen_hypercall_page)
ELFNOTE(Xen, XEN_ELFNOTE_FEATURES,
.ascii "!writable_page_tables|pae_pgdir_above_4gb")
ELFNOTE(Xen, XEN_ELFNOTE_SUPPORTED_FEATURES,
--
2.20.1
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