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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] x86/pv: Export pv_hypercall_table[] rather than working around it in several ways
The functions in compat.c are thing wrappers around the main hypercalls,
massaging certain parameters. However, they second-guess the content of
pv_hypercall_table[], which is problematic for the shim case. Instead,
arrange for them to call via function pointer, which removes the need for
pv_get_hypercall_handler().
With pv_hypercall_table[] exported, there is no need for
pv_hypercall_table_replace(), so its single callsite gets modified to cope.
The backing code behind __va(__pa()) is substantial, and there is no need to
calculate it repeatedly (Xen's .rodata is also contiguous in the directmap).
While adjusting the declarations, guard content in arch/x86/pv with CONFIG_PV.
The net difference is:
add/remove: 0/2 grow/shrink: 4/1 up/down: 176/-321 (-145)
function old new delta
pv_shim_setup_dom 1130 1266 +136
do_sched_op_compat 176 192 +16
compat_physdev_op_compat 90 106 +16
do_physdev_op_compat 98 106 +8
do_event_channel_op_compat 145 123 -22
pv_get_hypercall_handler 28 - -28
pv_hypercall_table_replace 271 - -271
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
---
xen/arch/x86/compat.c | 14 ++++++++++----
xen/arch/x86/pv/hypercall.c | 19 +------------------
xen/arch/x86/pv/shim.c | 21 +++++++++++++++------
xen/include/asm-x86/hypercall.h | 6 +++---
4 files changed, 29 insertions(+), 31 deletions(-)
diff --git a/xen/arch/x86/compat.c b/xen/arch/x86/compat.c
index 9d376a4..a40ec29 100644
--- a/xen/arch/x86/compat.c
+++ b/xen/arch/x86/compat.c
@@ -17,12 +17,14 @@ typedef long ret_t;
/* Legacy hypercall (as of 0x00030202). */
ret_t do_physdev_op_compat(XEN_GUEST_HANDLE(physdev_op_t) uop)
{
+ typeof(do_physdev_op) *fn =
+ (void *)pv_hypercall_table[__HYPERVISOR_physdev_op].native;
struct physdev_op op;
if ( unlikely(copy_from_guest(&op, uop, 1) != 0) )
return -EFAULT;
- return do_physdev_op(op.cmd, guest_handle_from_ptr(&uop.p->u, void));
+ return fn(op.cmd, guest_handle_from_ptr(&uop.p->u, void));
}
#ifndef COMPAT
@@ -30,11 +32,14 @@ ret_t do_physdev_op_compat(XEN_GUEST_HANDLE(physdev_op_t)
uop)
/* Legacy hypercall (as of 0x00030101). */
long do_sched_op_compat(int cmd, unsigned long arg)
{
+ typeof(do_sched_op) *fn =
+ (void *)pv_hypercall_table[__HYPERVISOR_sched_op].native;
+
switch ( cmd )
{
case SCHEDOP_yield:
case SCHEDOP_block:
- return do_sched_op(cmd, guest_handle_from_ptr(NULL, void));
+ return fn(cmd, guest_handle_from_ptr(NULL, void));
case SCHEDOP_shutdown:
TRACE_3D(TRC_SCHED_SHUTDOWN,
@@ -52,6 +57,8 @@ long do_sched_op_compat(int cmd, unsigned long arg)
/* Legacy hypercall (as of 0x00030202). */
long do_event_channel_op_compat(XEN_GUEST_HANDLE_PARAM(evtchn_op_t) uop)
{
+ typeof(do_event_channel_op) *fn =
+ (void *)pv_hypercall_table[__HYPERVISOR_event_channel_op].native;
struct evtchn_op op;
if ( unlikely(copy_from_guest(&op, uop, 1) != 0) )
@@ -69,8 +76,7 @@ long
do_event_channel_op_compat(XEN_GUEST_HANDLE_PARAM(evtchn_op_t) uop)
case EVTCHNOP_bind_ipi:
case EVTCHNOP_bind_vcpu:
case EVTCHNOP_unmask:
- return pv_get_hypercall_handler(__HYPERVISOR_event_channel_op, false)
- (op.cmd, (unsigned long)&uop.p->u, 0, 0, 0, 0);
+ return fn(op.cmd, guest_handle_from_ptr(&uop.p->u, void));
default:
return -ENOSYS;
diff --git a/xen/arch/x86/pv/hypercall.c b/xen/arch/x86/pv/hypercall.c
index 3b72d6a..bbc3011 100644
--- a/xen/arch/x86/pv/hypercall.c
+++ b/xen/arch/x86/pv/hypercall.c
@@ -32,7 +32,7 @@
#define do_arch_1 paging_domctl_continuation
-static const hypercall_table_t pv_hypercall_table[] = {
+const hypercall_table_t pv_hypercall_table[] = {
COMPAT_CALL(set_trap_table),
HYPERCALL(mmu_update),
COMPAT_CALL(set_gdt),
@@ -320,23 +320,6 @@ void hypercall_page_initialise_ring1_kernel(void
*hypercall_page)
*(u16 *)(p+ 6) = (HYPERCALL_VECTOR << 8) | 0xcd; /* int $xx */
}
-void __init pv_hypercall_table_replace(unsigned int hypercall,
- hypercall_fn_t * native,
- hypercall_fn_t *compat)
-{
-#define HANDLER_POINTER(f) \
- ((unsigned long *)__va(__pa(&pv_hypercall_table[hypercall].f)))
- write_atomic(HANDLER_POINTER(native), (unsigned long)native);
- write_atomic(HANDLER_POINTER(compat), (unsigned long)compat);
-#undef HANDLER_POINTER
-}
-
-hypercall_fn_t *pv_get_hypercall_handler(unsigned int hypercall, bool compat)
-{
- return compat ? pv_hypercall_table[hypercall].compat
- : pv_hypercall_table[hypercall].native;
-}
-
/*
* Local variables:
* mode: C
diff --git a/xen/arch/x86/pv/shim.c b/xen/arch/x86/pv/shim.c
index d5383dc..9651952 100644
--- a/xen/arch/x86/pv/shim.c
+++ b/xen/arch/x86/pv/shim.c
@@ -160,6 +160,7 @@ void __init pv_shim_setup_dom(struct domain *d,
l4_pgentry_t *l4start,
unsigned long console_va, unsigned long vphysmap,
start_info_t *si)
{
+ hypercall_table_t *rw_pv_hypercall_table;
uint64_t param = 0;
long rc;
@@ -205,12 +206,20 @@ void __init pv_shim_setup_dom(struct domain *d,
l4_pgentry_t *l4start,
mfn_x(console_mfn), vphysmap);
consoled_set_ring_addr(page);
}
- pv_hypercall_table_replace(__HYPERVISOR_event_channel_op,
- (hypercall_fn_t *)pv_shim_event_channel_op,
- (hypercall_fn_t *)pv_shim_event_channel_op);
- pv_hypercall_table_replace(__HYPERVISOR_grant_table_op,
- (hypercall_fn_t *)pv_shim_grant_table_op,
- (hypercall_fn_t *)pv_shim_grant_table_op);
+
+ /*
+ * Find a writeable mapping to pv_hypercall_table[] in the directmap
+ * insert some shim-specific hypercall handlers.
+ */
+ rw_pv_hypercall_table = __va(__pa(pv_hypercall_table));
+ rw_pv_hypercall_table[__HYPERVISOR_event_channel_op].native =
+ rw_pv_hypercall_table[__HYPERVISOR_event_channel_op].compat =
+ (hypercall_fn_t *)pv_shim_event_channel_op;
+
+ rw_pv_hypercall_table[__HYPERVISOR_grant_table_op].native =
+ rw_pv_hypercall_table[__HYPERVISOR_grant_table_op].compat =
+ (hypercall_fn_t *)pv_shim_grant_table_op;
+
guest = d;
/*
diff --git a/xen/include/asm-x86/hypercall.h b/xen/include/asm-x86/hypercall.h
index b9f3ecf..1cc2e37 100644
--- a/xen/include/asm-x86/hypercall.h
+++ b/xen/include/asm-x86/hypercall.h
@@ -25,12 +25,12 @@ typedef struct {
extern const hypercall_args_t hypercall_args_table[NR_hypercalls];
+#ifdef CONFIG_PV
+extern const hypercall_table_t pv_hypercall_table[];
void pv_hypercall(struct cpu_user_regs *regs);
void hypercall_page_initialise_ring3_kernel(void *hypercall_page);
void hypercall_page_initialise_ring1_kernel(void *hypercall_page);
-void pv_hypercall_table_replace(unsigned int hypercall, hypercall_fn_t *
native,
- hypercall_fn_t *compat);
-hypercall_fn_t *pv_get_hypercall_handler(unsigned int hypercall, bool compat);
+#endif
/*
* Both do_mmuext_op() and do_mmu_update():
--
2.1.4
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