diff mbox series

[v2,1/5] KVM: Add arch specific interfaces for sampling guest callchains

Message ID SY4P282MB10840154D4F09917D6528BC69DCFA@SY4P282MB1084.AUSP282.PROD.OUTLOOK.COM
State New
Headers
Series perf: KVM: Enable callchains for guests |

Commit Message

Tianyi Liu Oct. 8, 2023, 2:52 p.m. UTC 
  This patch adds three architecture specific interfaces and x86
implementations used by `perf kvm`:

- kvm_arch_vcpu_get_frame_pointer: Return the frame pointer of vcpu,
  for x86 it's RBP, and for arm64 it's x29.

- kvm_arch_vcpu_read_virt: Read data from a virtual address
  of the given guest vm.

- kvm_arch_vcpu_is_64bit: Return whether the vcpu is working in 64-bit
  mode. It's used for determining the size of a stack frame.

Since arm64 hasn't provided some foundational infrastructure,
stub the arm64 implementation for now because it's a bit complex.

Signed-off-by: Tianyi Liu <i.pear@outlook.com>
---
 arch/arm64/kvm/arm.c     | 17 +++++++++++++++++
 arch/x86/kvm/x86.c       | 18 ++++++++++++++++++
 include/linux/kvm_host.h |  4 ++++
 3 files changed, 39 insertions(+)

Comments

kernel test robot Oct. 8, 2023, 9:12 p.m. UTC | #1 
Hi Tianyi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 8a749fd1a8720d4619c91c8b6e7528c0a355c0aa]

url:    https://github.com/intel-lab-lkp/linux/commits/Tianyi-Liu/KVM-Add-arch-specific-interfaces-for-sampling-guest-callchains/20231008-230042
base:   8a749fd1a8720d4619c91c8b6e7528c0a355c0aa
patch link:    https://lore.kernel.org/r/SY4P282MB10840154D4F09917D6528BC69DCFA%40SY4P282MB1084.AUSP282.PROD.OUTLOOK.COM
patch subject: [PATCH v2 1/5] KVM: Add arch specific interfaces for sampling guest callchains
config: arm64-randconfig-003-20231009 (https://download.01.org/0day-ci/archive/20231009/202310090448.ffbVfkHi-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231009/202310090448.ffbVfkHi-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310090448.ffbVfkHi-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/uapi/linux/posix_types.h:5,
                    from include/uapi/linux/types.h:14,
                    from include/linux/types.h:6,
                    from include/linux/kasan-checks.h:5,
                    from include/asm-generic/rwonce.h:26,
                    from arch/arm64/include/asm/rwonce.h:71,
                    from include/linux/compiler.h:246,
                    from include/asm-generic/bug.h:5,
                    from arch/arm64/include/asm/bug.h:26,
                    from include/linux/bug.h:5,
                    from arch/arm64/kvm/arm.c:7:
   arch/arm64/kvm/arm.c: In function 'kvm_arch_vcpu_get_frame_pointer':
>> include/linux/stddef.h:8:14: warning: returning 'void *' from a function with return type 'long unsigned int' makes integer from pointer without a cast [-Wint-conversion]
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/arm.c:578:16: note: in expansion of macro 'NULL'
     578 |         return NULL;
         |                ^~~~


vim +8 include/linux/stddef.h

^1da177e4c3f41 Linus Torvalds   2005-04-16  6  
^1da177e4c3f41 Linus Torvalds   2005-04-16  7  #undef NULL
^1da177e4c3f41 Linus Torvalds   2005-04-16 @8  #define NULL ((void *)0)
6e218287432472 Richard Knutsson 2006-09-30  9
kernel test robot Oct. 8, 2023, 9:32 p.m. UTC | #2 
Hi Tianyi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 8a749fd1a8720d4619c91c8b6e7528c0a355c0aa]

url:    https://github.com/intel-lab-lkp/linux/commits/Tianyi-Liu/KVM-Add-arch-specific-interfaces-for-sampling-guest-callchains/20231008-230042
base:   8a749fd1a8720d4619c91c8b6e7528c0a355c0aa
patch link:    https://lore.kernel.org/r/SY4P282MB10840154D4F09917D6528BC69DCFA%40SY4P282MB1084.AUSP282.PROD.OUTLOOK.COM
patch subject: [PATCH v2 1/5] KVM: Add arch specific interfaces for sampling guest callchains
config: x86_64-defconfig (https://download.01.org/0day-ci/archive/20231009/202310090559.wzrojQni-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-12) 11.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231009/202310090559.wzrojQni-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310090559.wzrojQni-lkp@intel.com/

All warnings (new ones prefixed by >>):

   arch/x86/kvm/x86.c: In function 'kvm_arch_vcpu_read_virt':
>> arch/x86/kvm/x86.c:12917:42: warning: passing argument 2 of 'kvm_read_guest_virt' makes integer from pointer without a cast [-Wint-conversion]
   12917 |         return kvm_read_guest_virt(vcpu, addr, dest, length, &e) == X86EMUL_CONTINUE;
         |                                          ^~~~
         |                                          |
         |                                          void *
   arch/x86/kvm/x86.c:7388:38: note: expected 'gva_t' {aka 'long unsigned int'} but argument is of type 'void *'
    7388 |                                gva_t addr, void *val, unsigned int bytes,
         |                                ~~~~~~^~~~


vim +/kvm_read_guest_virt +12917 arch/x86/kvm/x86.c

 12911	
 12912	bool kvm_arch_vcpu_read_virt(struct kvm_vcpu *vcpu, void *addr, void *dest, unsigned int length)
 12913	{
 12914		struct x86_exception e;
 12915	
 12916		/* Return true on success */
 12917		return kvm_read_guest_virt(vcpu, addr, dest, length, &e) == X86EMUL_CONTINUE;
 12918	}
 12919
kernel test robot Oct. 8, 2023, 10:25 p.m. UTC | #3 
Hi Tianyi,

kernel test robot noticed the following build errors:

[auto build test ERROR on 8a749fd1a8720d4619c91c8b6e7528c0a355c0aa]

url:    https://github.com/intel-lab-lkp/linux/commits/Tianyi-Liu/KVM-Add-arch-specific-interfaces-for-sampling-guest-callchains/20231008-230042
base:   8a749fd1a8720d4619c91c8b6e7528c0a355c0aa
patch link:    https://lore.kernel.org/r/SY4P282MB10840154D4F09917D6528BC69DCFA%40SY4P282MB1084.AUSP282.PROD.OUTLOOK.COM
patch subject: [PATCH v2 1/5] KVM: Add arch specific interfaces for sampling guest callchains
config: x86_64-rhel-8.3-rust (https://download.01.org/0day-ci/archive/20231009/202310090652.6TMWiCuU-lkp@intel.com/config)
compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231009/202310090652.6TMWiCuU-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310090652.6TMWiCuU-lkp@intel.com/

All errors (new ones prefixed by >>):

>> arch/x86/kvm/x86.c:12917:35: error: incompatible pointer to integer conversion passing 'void *' to parameter of type 'gva_t' (aka 'unsigned long') [-Wint-conversion]
           return kvm_read_guest_virt(vcpu, addr, dest, length, &e) == X86EMUL_CONTINUE;
                                            ^~~~
   arch/x86/kvm/x86.c:7403:19: note: passing argument to parameter here
   EXPORT_SYMBOL_GPL(kvm_read_guest_virt);
                     ^
   1 error generated.


vim +12917 arch/x86/kvm/x86.c

 12911	
 12912	bool kvm_arch_vcpu_read_virt(struct kvm_vcpu *vcpu, void *addr, void *dest, unsigned int length)
 12913	{
 12914		struct x86_exception e;
 12915	
 12916		/* Return true on success */
 12917		return kvm_read_guest_virt(vcpu, addr, dest, length, &e) == X86EMUL_CONTINUE;
 12918	}
 12919
Tianyi Liu Oct. 9, 2023, 3:17 a.m. UTC | #4 
> All warnings (new ones prefixed by >>):
> 
>    arch/x86/kvm/x86.c: In function 'kvm_arch_vcpu_read_virt':
> >> arch/x86/kvm/x86.c:12917:42: warning: passing argument 2 of 'kvm_read_guest_virt' makes integer from pointer without a cast [-Wint-conversion]
>    12917 |         return kvm_read_guest_virt(vcpu, addr, dest, length, &e) == X86EMUL_CONTINUE;
>          |                                          ^~~~
>          |                                          |
>          |                                          void *
>    arch/x86/kvm/x86.c:7388:38: note: expected 'gva_t' {aka 'long unsigned int'} but argument is of type 'void *'
>     7388 |                                gva_t addr, void *val, unsigned int bytes,
>          |                                ~~~~~~^~~~
> 

Terribly sorry for the build warnings, which is caused by type casting.
Will be fixed in the next version.
diff mbox series

Patch

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 4866b3f7b..b57b88c58 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -571,6 +571,23 @@  unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
 {
 	return *vcpu_pc(vcpu);
 }
+
+unsigned long kvm_arch_vcpu_get_frame_pointer(struct kvm_vcpu *vcpu)
+{
+	/* TODO: implement */
+	return NULL;
+}
+
+bool kvm_arch_vcpu_read_virt(struct kvm_vcpu *vcpu, void *addr, void *dest, unsigned int length)
+{
+	/* TODO: implement */
+	return false;
+}
+
+bool kvm_arch_vcpu_is_64bit(struct kvm_vcpu *vcpu)
+{
+	return !vcpu_mode_is_32bit(vcpu);
+}
 #endif
 
 static int kvm_vcpu_initialized(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9f18b06bb..17dea02b7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12904,6 +12904,24 @@  unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
 	return kvm_rip_read(vcpu);
 }
 
+unsigned long kvm_arch_vcpu_get_frame_pointer(struct kvm_vcpu *vcpu)
+{
+	return kvm_register_read_raw(vcpu, VCPU_REGS_RBP);
+}
+
+bool kvm_arch_vcpu_read_virt(struct kvm_vcpu *vcpu, void *addr, void *dest, unsigned int length)
+{
+	struct x86_exception e;
+
+	/* Return true on success */
+	return kvm_read_guest_virt(vcpu, addr, dest, length, &e) == X86EMUL_CONTINUE;
+}
+
+bool kvm_arch_vcpu_is_64bit(struct kvm_vcpu *vcpu)
+{
+	return is_64_bit_mode(vcpu);
+}
+
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
 	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index fb6c6109f..f92f1a9c8 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1595,6 +1595,10 @@  static inline bool kvm_arch_intc_initialized(struct kvm *kvm)
 
 #ifdef CONFIG_GUEST_PERF_EVENTS
 unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu);
+unsigned long kvm_arch_vcpu_get_frame_pointer(struct kvm_vcpu *vcpu);
+bool kvm_arch_vcpu_read_virt(struct kvm_vcpu *vcpu, void *addr, void *dest,
+			     unsigned int length);
+bool kvm_arch_vcpu_is_64bit(struct kvm_vcpu *vcpu);
 
 void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void));
 void kvm_unregister_perf_callbacks(void);