From: Grygorii Strashko <[email protected]>
Xen uses below pattern for raw_x_guest() functions:
define raw_copy_to_guest(dst, src, len) \
(is_hvm_vcpu(current) ? \
copy_to_user_hvm((dst), (src), (len)) : \
copy_to_guest_pv(dst, src, len))
This pattern works depending on CONFIG_PV/CONFIG_HVM as:
- PV=y and HVM=y
Proper guest access function is selected depending on domain type.
- PV=y and HVM=n
Only PV domains are possible. is_hvm_domain/vcpu() will constify to "false"
and compiler will optimize code and skip HVM specific part.
- PV=n and HVM=y
Only HVM domains are possible. is_hvm_domain/vcpu() will not be constified.
No PV specific code will be optimized by compiler.
- PV=n and HVM=n
No guests should possible. The code will still follow PV path.
Rework raw_x_guest() code to use static inline functions which account for
above PV/HVM possible configurations with main intention to optimize code
for (PV=n and HVM=y) case.
For the case (PV=n and HVM=n) return "len" value indicating a failure (no
guests should be possible in this case, which means no access to guest
memory should ever happen).
The measured (bloat-o-meter) improvement for (PV=n and HVM=y) case is about
-11K.
[[email protected]: Suggested to use static inline functions vs
macro combinations]
Suggested-by: Teddy Astie <[email protected]>
Signed-off-by: Grygorii Strashko <[email protected]>
---
changes in v5:
- rebase
- drop moving usercopy.c as it is not needed since commit 7370966d1cb7
("x86: move / split usercopy.c to / into arch-specific library")
changes in v4:
- move usercopy.c into arch/x86/pv/
- rework to always dynamically check for HVM vcpu(domain) by using is_hvm_vcpu()
as requested by Jan Beulich
changes in v3:
- add raw_use_hvm_access() wrapper
changes in v2:
- use static inline functions instead of macro combinations
xen/arch/x86/include/asm/guest_access.h | 78 ++++++++++++++++++-------
1 file changed, 58 insertions(+), 20 deletions(-)
diff --git a/xen/arch/x86/include/asm/guest_access.h
b/xen/arch/x86/include/asm/guest_access.h
index 69716c8b41bb..f0e56b112e14 100644
--- a/xen/arch/x86/include/asm/guest_access.h
+++ b/xen/arch/x86/include/asm/guest_access.h
@@ -13,26 +13,64 @@
#include <asm/hvm/guest_access.h>
/* Raw access functions: no type checking. */
-#define raw_copy_to_guest(dst, src, len) \
- (is_hvm_vcpu(current) ? \
- copy_to_user_hvm((dst), (src), (len)) : \
- copy_to_guest_pv(dst, src, len))
-#define raw_copy_from_guest(dst, src, len) \
- (is_hvm_vcpu(current) ? \
- copy_from_user_hvm((dst), (src), (len)) : \
- copy_from_guest_pv(dst, src, len))
-#define raw_clear_guest(dst, len) \
- (is_hvm_vcpu(current) ? \
- clear_user_hvm((dst), (len)) : \
- clear_guest_pv(dst, len))
-#define __raw_copy_to_guest(dst, src, len) \
- (is_hvm_vcpu(current) ? \
- copy_to_user_hvm((dst), (src), (len)) : \
- __copy_to_guest_pv(dst, src, len))
-#define __raw_copy_from_guest(dst, src, len) \
- (is_hvm_vcpu(current) ? \
- copy_from_user_hvm((dst), (src), (len)) : \
- __copy_from_guest_pv(dst, src, len))
+static inline unsigned int raw_copy_to_guest(void *dst, const void *src,
+ unsigned int len)
+{
+ if ( is_hvm_vcpu(current) )
+ return copy_to_user_hvm(dst, src, len);
+
+ if ( !IS_ENABLED(CONFIG_PV) )
+ return len;
+
+ return copy_to_guest_pv(dst, src, len);
+}
+
+static inline unsigned int raw_copy_from_guest(void *dst, const void *src,
+ unsigned int len)
+{
+ if ( is_hvm_vcpu(current) )
+ return copy_from_user_hvm(dst, src, len);
+
+ if ( !IS_ENABLED(CONFIG_PV) )
+ return len;
+
+ return copy_from_guest_pv(dst, src, len);
+}
+
+static inline unsigned int raw_clear_guest(void *dst, unsigned int len)
+{
+ if ( is_hvm_vcpu(current) )
+ return clear_user_hvm(dst, len);
+
+ if ( !IS_ENABLED(CONFIG_PV) )
+ return len;
+
+ return clear_guest_pv(dst, len);
+}
+
+static inline unsigned int __raw_copy_to_guest(void *dst, const void *src,
+ unsigned int len)
+{
+ if ( is_hvm_vcpu(current) )
+ return copy_to_user_hvm(dst, src, len);
+
+ if ( !IS_ENABLED(CONFIG_PV) )
+ return len;
+
+ return __copy_to_guest_pv(dst, src, len);
+}
+
+static inline unsigned int __raw_copy_from_guest(void *dst, const void *src,
+ unsigned int len)
+{
+ if ( is_hvm_vcpu(current) )
+ return copy_from_user_hvm(dst, src, len);
+
+ if ( !IS_ENABLED(CONFIG_PV) )
+ return len;
+
+ return __copy_from_guest_pv(dst, src, len);
+}
/*
* Pre-validate a guest handle.
--
2.34.1
