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Date: Mon, 23 Nov 2009 16:05:59 +0200
From: Gleb Natapov <gleb@...hat.com>
To: kvm@...r.kernel.org
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, avi@...hat.com,
mingo@...e.hu, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
hpa@...or.com, riel@...hat.com
Subject: [PATCH v2 04/12] Add "handle page fault" PV helper.
Allow paravirtualized guest to do special handling for some page faults.
Ingo's concerns not yet addressed here. What was the conclusion of previous
discussion?
Signed-off-by: Gleb Natapov <gleb@...hat.com>
---
arch/x86/include/asm/paravirt.h | 7 +++++++
arch/x86/include/asm/paravirt_types.h | 4 ++++
arch/x86/kernel/paravirt.c | 8 ++++++++
arch/x86/kernel/paravirt_patch_32.c | 8 ++++++++
arch/x86/kernel/paravirt_patch_64.c | 7 +++++++
arch/x86/mm/fault.c | 3 +++
6 files changed, 37 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index efb3899..5203da1 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -6,6 +6,7 @@
#ifdef CONFIG_PARAVIRT
#include <asm/pgtable_types.h>
#include <asm/asm.h>
+#include <asm/ptrace.h>
#include <asm/paravirt_types.h>
@@ -710,6 +711,12 @@ static inline void arch_end_context_switch(struct task_struct *next)
PVOP_VCALL1(pv_cpu_ops.end_context_switch, next);
}
+static inline int arch_handle_page_fault(struct pt_regs *regs,
+ unsigned long error_code)
+{
+ return PVOP_CALL2(int, pv_cpu_ops.handle_pf, regs, error_code);
+}
+
#define __HAVE_ARCH_ENTER_LAZY_MMU_MODE
static inline void arch_enter_lazy_mmu_mode(void)
{
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 9357473..bcc39b3 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -186,6 +186,7 @@ struct pv_cpu_ops {
void (*start_context_switch)(struct task_struct *prev);
void (*end_context_switch)(struct task_struct *next);
+ int (*handle_pf)(struct pt_regs *regs, unsigned long error_code);
};
struct pv_irq_ops {
@@ -385,6 +386,7 @@ extern struct pv_lock_ops pv_lock_ops;
unsigned paravirt_patch_nop(void);
unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len);
unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len);
+unsigned paravirt_patch_ret_0(void *insnbuf, unsigned len);
unsigned paravirt_patch_ignore(unsigned len);
unsigned paravirt_patch_call(void *insnbuf,
const void *target, u16 tgt_clobbers,
@@ -676,8 +678,10 @@ void paravirt_leave_lazy_mmu(void);
void _paravirt_nop(void);
u32 _paravirt_ident_32(u32);
u64 _paravirt_ident_64(u64);
+unsigned long _paravirt_ret_0(void);
#define paravirt_nop ((void *)_paravirt_nop)
+#define paravirt_ret_0 ((void *)_paravirt_ret_0)
/* These all sit in the .parainstructions section to tell us what to patch. */
struct paravirt_patch_site {
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 1b1739d..7d8f37b 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -54,6 +54,11 @@ u64 _paravirt_ident_64(u64 x)
return x;
}
+unsigned long _paravirt_ret_0(void)
+{
+ return 0;
+}
+
void __init default_banner(void)
{
printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
@@ -154,6 +159,8 @@ unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
ret = paravirt_patch_ident_32(insnbuf, len);
else if (opfunc == _paravirt_ident_64)
ret = paravirt_patch_ident_64(insnbuf, len);
+ else if (opfunc == _paravirt_ret_0)
+ ret = paravirt_patch_ret_0(insnbuf, len);
else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit) ||
@@ -380,6 +387,7 @@ struct pv_cpu_ops pv_cpu_ops = {
.start_context_switch = paravirt_nop,
.end_context_switch = paravirt_nop,
+ .handle_pf = paravirt_ret_0,
};
struct pv_apic_ops pv_apic_ops = {
diff --git a/arch/x86/kernel/paravirt_patch_32.c b/arch/x86/kernel/paravirt_patch_32.c
index d9f32e6..de006b1 100644
--- a/arch/x86/kernel/paravirt_patch_32.c
+++ b/arch/x86/kernel/paravirt_patch_32.c
@@ -12,6 +12,8 @@ DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax");
DEF_NATIVE(pv_cpu_ops, clts, "clts");
DEF_NATIVE(pv_cpu_ops, read_tsc, "rdtsc");
+DEF_NATIVE(, mov0, "xor %eax, %eax");
+
unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len)
{
/* arg in %eax, return in %eax */
@@ -24,6 +26,12 @@ unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len)
return 0;
}
+unsigned paravirt_patch_ret_0(void *insnbuf, unsigned len)
+{
+ return paravirt_patch_insns(insnbuf, len,
+ start__mov0, end__mov0);
+}
+
unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
unsigned long addr, unsigned len)
{
diff --git a/arch/x86/kernel/paravirt_patch_64.c b/arch/x86/kernel/paravirt_patch_64.c
index 3f08f34..d685e7d 100644
--- a/arch/x86/kernel/paravirt_patch_64.c
+++ b/arch/x86/kernel/paravirt_patch_64.c
@@ -21,6 +21,7 @@ DEF_NATIVE(pv_cpu_ops, swapgs, "swapgs");
DEF_NATIVE(, mov32, "mov %edi, %eax");
DEF_NATIVE(, mov64, "mov %rdi, %rax");
+DEF_NATIVE(, mov0, "xor %rax, %rax");
unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len)
{
@@ -34,6 +35,12 @@ unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len)
start__mov64, end__mov64);
}
+unsigned paravirt_patch_ret_0(void *insnbuf, unsigned len)
+{
+ return paravirt_patch_insns(insnbuf, len,
+ start__mov0, end__mov0);
+}
+
unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
unsigned long addr, unsigned len)
{
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index f4cee90..14707dc 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -952,6 +952,9 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code)
int write;
int fault;
+ if (arch_handle_page_fault(regs, error_code))
+ return;
+
tsk = current;
mm = tsk->mm;
--
1.6.5
--
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