diff mbox series

[RESEND,2/2] KVM: X86: Expose bus lock debug exception to guest

Message ID 20210108064924.1677-3-chenyi.qiang@intel.com (mailing list archive)
State New, archived
Headers show
Series Add KVM support for bus lock debug exception | expand

Commit Message

Chenyi Qiang Jan. 8, 2021, 6:49 a.m. UTC
Bus lock debug exception is an ability to notify the kernel by an #DB
trap after the instruction acquires a bus lock and is executed when
CPL>0. This allows the kernel to enforce user application throttling or
mitigations.

Existence of bus lock debug exception is enumerated via
CPUID.(EAX=7,ECX=0).ECX[24]. Software can enable these exceptions by
setting bit 2 of the MSR_IA32_DEBUGCTL. Expose the CPUID to guest and
emulate the MSR handling when guest enables it.

Since SVM already has specific handlers of MSR_IA32_DEBUGMSR in the
svm_get/set_msr, move x86 commmon part to VMX and add the bus lock debug
exception support.

Co-developed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
---
 arch/x86/kvm/cpuid.c   |  3 ++-
 arch/x86/kvm/vmx/vmx.c | 23 +++++++++++++++++++++--
 arch/x86/kvm/x86.c     | 16 ++--------------
 arch/x86/kvm/x86.h     |  2 ++
 4 files changed, 27 insertions(+), 17 deletions(-)

Comments

kernel test robot Jan. 8, 2021, 6:16 p.m. UTC | #1
Hi Chenyi,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on kvm/linux-next]
[also build test ERROR on v5.11-rc2 next-20210108]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Chenyi-Qiang/Add-KVM-support-for-bus-lock-debug-exception/20210108-144848
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
config: i386-randconfig-r015-20210108 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/fd0365cd4650a48a76379269b7cebd40ee38e52c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Chenyi-Qiang/Add-KVM-support-for-bus-lock-debug-exception/20210108-144848
        git checkout fd0365cd4650a48a76379269b7cebd40ee38e52c
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from arch/x86/kvm/cpuid.c:21:
   arch/x86/kvm/cpuid.c: In function 'kvm_set_cpu_caps':
>> arch/x86/kvm/cpuid.h:98:42: error: 'X86_FEATURE_BUS_LOCK_DETECT' undeclared (first use in this function); did you mean 'X86_FEATURE_SPLIT_LOCK_DETECT'?
      98 | #define feature_bit(name)  __feature_bit(X86_FEATURE_##name)
         |                                          ^~~~~~~~~~~~
   arch/x86/kvm/cpuid.c:55:11: note: in expansion of macro 'feature_bit'
      55 | #define F feature_bit
         |           ^~~~~~~~~~~
   arch/x86/kvm/cpuid.c:406:3: note: in expansion of macro 'F'
     406 |   F(BUS_LOCK_DETECT)
         |   ^
   arch/x86/kvm/cpuid.h:98:42: note: each undeclared identifier is reported only once for each function it appears in
      98 | #define feature_bit(name)  __feature_bit(X86_FEATURE_##name)
         |                                          ^~~~~~~~~~~~
   arch/x86/kvm/cpuid.c:55:11: note: in expansion of macro 'feature_bit'
      55 | #define F feature_bit
         |           ^~~~~~~~~~~
   arch/x86/kvm/cpuid.c:406:3: note: in expansion of macro 'F'
     406 |   F(BUS_LOCK_DETECT)
         |   ^
--
   In file included from include/linux/export.h:43,
                    from include/linux/linkage.h:7,
                    from include/linux/fs.h:5,
                    from include/linux/highmem.h:5,
                    from arch/x86/kvm/vmx/vmx.c:16:
   arch/x86/kvm/vmx/vmx.c: In function 'vmx_set_msr':
>> arch/x86/kvm/vmx/vmx.c:151:20: error: 'DEBUGCTLMSR_BUS_LOCK_DETECT' undeclared (first use in this function)
     151 |  DEBUGCTLMSR_BTF | DEBUGCTLMSR_BUS_LOCK_DETECT)
         |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler.h:58:52: note: in definition of macro '__trace_if_var'
      58 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
         |                                                    ^~~~
   arch/x86/kvm/vmx/vmx.c:2011:3: note: in expansion of macro 'if'
    2011 |   if (data & ~MSR_VMX_SUPPORTED_DEBUGCTL)
         |   ^~
   arch/x86/kvm/vmx/vmx.c:2011:15: note: in expansion of macro 'MSR_VMX_SUPPORTED_DEBUGCTL'
    2011 |   if (data & ~MSR_VMX_SUPPORTED_DEBUGCTL)
         |               ^~~~~~~~~~~~~~~~~~~~~~~~~~
   arch/x86/kvm/vmx/vmx.c:151:20: note: each undeclared identifier is reported only once for each function it appears in
     151 |  DEBUGCTLMSR_BTF | DEBUGCTLMSR_BUS_LOCK_DETECT)
         |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler.h:58:52: note: in definition of macro '__trace_if_var'
      58 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
         |                                                    ^~~~
   arch/x86/kvm/vmx/vmx.c:2011:3: note: in expansion of macro 'if'
    2011 |   if (data & ~MSR_VMX_SUPPORTED_DEBUGCTL)
         |   ^~
   arch/x86/kvm/vmx/vmx.c:2011:15: note: in expansion of macro 'MSR_VMX_SUPPORTED_DEBUGCTL'
    2011 |   if (data & ~MSR_VMX_SUPPORTED_DEBUGCTL)
         |               ^~~~~~~~~~~~~~~~~~~~~~~~~~
>> arch/x86/kvm/vmx/vmx.c:2016:30: error: 'X86_FEATURE_BUS_LOCK_DETECT' undeclared (first use in this function); did you mean 'X86_FEATURE_SPLIT_LOCK_DETECT'?
    2016 |       !guest_cpuid_has(vcpu, X86_FEATURE_BUS_LOCK_DETECT))
         |                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler.h:58:52: note: in definition of macro '__trace_if_var'
      58 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
         |                                                    ^~~~
   arch/x86/kvm/vmx/vmx.c:2014:3: note: in expansion of macro 'if'
    2014 |   if (!msr_info->host_initiated &&
         |   ^~


vim +98 arch/x86/kvm/cpuid.h

a0a2260c12d8658 Sean Christopherson 2019-12-17  97  
87382003e355592 Sean Christopherson 2019-12-17 @98  #define feature_bit(name)  __feature_bit(X86_FEATURE_##name)
87382003e355592 Sean Christopherson 2019-12-17  99  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Paolo Bonzini Jan. 26, 2021, 4:33 p.m. UTC | #2
On 08/01/21 19:16, kernel test robot wrote:
> Hi Chenyi,
> 
> Thank you for the patch! Yet something to improve:
> 
> [auto build test ERROR on kvm/linux-next]
> [also build test ERROR on v5.11-rc2 next-20210108]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]

What is the status of the patch to introduce X86_FEATURE_BUS_LOCK_DETECT 
(I saw 
https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2389369.html)?

Paolo
Chenyi Qiang Jan. 27, 2021, 12:57 a.m. UTC | #3
On 1/27/2021 12:33 AM, Paolo Bonzini wrote:
> On 08/01/21 19:16, kernel test robot wrote:
>> Hi Chenyi,
>>
>> Thank you for the patch! Yet something to improve:
>>
>> [auto build test ERROR on kvm/linux-next]
>> [also build test ERROR on v5.11-rc2 next-20210108]
>> [If your patch is applied to the wrong git tree, kindly drop us a note.
>> And when submitting patch, we suggest to use '--base' as documented in
>> https://git-scm.com/docs/git-format-patch]
> 
> What is the status of the patch to introduce X86_FEATURE_BUS_LOCK_DETECT 
> (I saw 
> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2389369.html)?
> 
> Paolo

Fenghua sent the v4 patch and pinged x86 maintainers, but still no feedback.
https://lore.kernel.org/lkml/YA8bkmYjShKwmyXx@otcwcpicx3.sc.intel.com/

>
Paolo Bonzini Jan. 27, 2021, 12:31 p.m. UTC | #4
On 27/01/21 01:57, Chenyi Qiang wrote:
>>
>> What is the status of the patch to introduce 
>> X86_FEATURE_BUS_LOCK_DETECT (I saw 
>> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2389369.html)? 
>>
>>
>> Paolo
> 
> Fenghua sent the v4 patch and pinged x86 maintainers, but still no 
> feedback.
> https://lore.kernel.org/lkml/YA8bkmYjShKwmyXx@otcwcpicx3.sc.intel.com/

Ok, please include it when you repost.  Thanks!

Paolo
diff mbox series

Patch

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 13036cf0b912..ea7c593794d2 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -402,7 +402,8 @@  void kvm_set_cpu_caps(void)
 		F(AVX512VBMI) | F(LA57) | F(PKU) | 0 /*OSPKE*/ | F(RDPID) |
 		F(AVX512_VPOPCNTDQ) | F(UMIP) | F(AVX512_VBMI2) | F(GFNI) |
 		F(VAES) | F(VPCLMULQDQ) | F(AVX512_VNNI) | F(AVX512_BITALG) |
-		F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | 0 /*WAITPKG*/
+		F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | 0 /*WAITPKG*/ |
+		F(BUS_LOCK_DETECT)
 	);
 	/* Set LA57 based on hardware capability. */
 	if (cpuid_ecx(7) & F(LA57))
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 13c9bcc4d9d9..39f28f90bbb4 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -147,6 +147,9 @@  module_param(allow_smaller_maxphyaddr, bool, S_IRUGO);
 	RTIT_STATUS_ERROR | RTIT_STATUS_STOPPED | \
 	RTIT_STATUS_BYTECNT))
 
+#define MSR_VMX_SUPPORTED_DEBUGCTL (DEBUGCTLMSR_LBR | \
+	DEBUGCTLMSR_BTF | DEBUGCTLMSR_BUS_LOCK_DETECT)
+
 /*
  * List of MSRs that can be directly passed to the guest.
  * In addition to these x2apic and PT MSRs are handled specially.
@@ -1924,6 +1927,9 @@  static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		    !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
 			return 1;
 		goto find_uret_msr;
+	case MSR_IA32_DEBUGCTLMSR:
+		msr_info->data = vmcs_read64(GUEST_IA32_DEBUGCTL);
+		break;
 	default:
 	find_uret_msr:
 		msr = vmx_find_uret_msr(vmx, msr_info->index);
@@ -2002,9 +2008,22 @@  static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 						VM_EXIT_SAVE_DEBUG_CONTROLS)
 			get_vmcs12(vcpu)->guest_ia32_debugctl = data;
 
-		ret = kvm_set_msr_common(vcpu, msr_info);
-		break;
+		if (data & ~MSR_VMX_SUPPORTED_DEBUGCTL)
+			return 1;
 
+		if (!msr_info->host_initiated &&
+		    (data & DEBUGCTLMSR_BUS_LOCK_DETECT) &&
+		    !guest_cpuid_has(vcpu, X86_FEATURE_BUS_LOCK_DETECT))
+			return 1;
+
+		if (data & (DEBUGCTLMSR_BTF|DEBUGCTLMSR_LBR)) {
+			if (report_ignored_msrs)
+				vcpu_unimpl(vcpu, "%s: BTF|LBR in IA32_DEBUGCTLMSR 0x%llx, nop\n",
+					    __func__, data);
+			data &= ~(DEBUGCTLMSR_BTF|DEBUGCTLMSR_LBR);
+		}
+		vmcs_write64(GUEST_IA32_DEBUGCTL, data);
+		return 0;
 	case MSR_IA32_BNDCFGS:
 		if (!kvm_mpx_supported() ||
 		    (!msr_info->host_initiated &&
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 06de2b9e57f3..d4a601482794 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -116,8 +116,9 @@  EXPORT_SYMBOL_GPL(kvm_x86_ops);
 static bool __read_mostly ignore_msrs = 0;
 module_param(ignore_msrs, bool, S_IRUGO | S_IWUSR);
 
-static bool __read_mostly report_ignored_msrs = true;
+bool __read_mostly report_ignored_msrs = true;
 module_param(report_ignored_msrs, bool, S_IRUGO | S_IWUSR);
+EXPORT_SYMBOL_GPL(report_ignored_msrs);
 
 unsigned int min_timer_period_us = 200;
 module_param(min_timer_period_us, uint, S_IRUGO | S_IWUSR);
@@ -3067,18 +3068,6 @@  int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 			return 1;
 		}
 		break;
-	case MSR_IA32_DEBUGCTLMSR:
-		if (!data) {
-			/* We support the non-activated case already */
-			break;
-		} else if (data & ~(DEBUGCTLMSR_LBR | DEBUGCTLMSR_BTF)) {
-			/* Values other than LBR and BTF are vendor-specific,
-			   thus reserved and should throw a #GP */
-			return 1;
-		} else if (report_ignored_msrs)
-			vcpu_unimpl(vcpu, "%s: MSR_IA32_DEBUGCTLMSR 0x%llx, nop\n",
-				    __func__, data);
-		break;
 	case 0x200 ... 0x2ff:
 		return kvm_mtrr_set_msr(vcpu, msr, data);
 	case MSR_IA32_APICBASE:
@@ -3351,7 +3340,6 @@  int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	switch (msr_info->index) {
 	case MSR_IA32_PLATFORM_ID:
 	case MSR_IA32_EBL_CR_POWERON:
-	case MSR_IA32_DEBUGCTLMSR:
 	case MSR_IA32_LASTBRANCHFROMIP:
 	case MSR_IA32_LASTBRANCHTOIP:
 	case MSR_IA32_LASTINTFROMIP:
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index c5ee0f5ce0f1..f13aa386e536 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -296,6 +296,8 @@  extern int pi_inject_timer;
 
 extern struct static_key kvm_no_apic_vcpu;
 
+extern bool report_ignored_msrs;
+
 static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec)
 {
 	return pvclock_scale_delta(nsec, vcpu->arch.virtual_tsc_mult,