* [PATCH] KVM: x86: fix DR6 delivery for emulated hardware breakpoint
@ 2020-05-05 11:34 Paolo Bonzini
2020-05-05 14:15 ` Peter Xu
2020-05-06 0:33 ` kbuild test robot
0 siblings, 2 replies; 3+ messages in thread
From: Paolo Bonzini @ 2020-05-05 11:34 UTC (permalink / raw)
To: linux-kernel, kvm; +Cc: jmattson, peterx
Go through kvm_queue_exception_p so that the payload is correctly delivered
through the exit qualification, and add a kvm_update_dr6 call to
kvm_deliver_exception_payload that is needed on AMD.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/x86.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c5835f9cb9ad..8f61cb15f147 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -473,6 +473,7 @@ void kvm_deliver_exception_payload(struct kvm_vcpu *vcpu)
* breakpoint), it is reserved and must be zero in DR6.
*/
vcpu->arch.dr6 &= ~BIT(12);
+ kvm_update_dr6(vcpu);
break;
case PF_VECTOR:
vcpu->arch.cr2 = payload;
@@ -6731,9 +6732,7 @@ static bool kvm_vcpu_check_breakpoint(struct kvm_vcpu *vcpu, int *r)
vcpu->arch.db);
if (dr6 != 0) {
- vcpu->arch.dr6 &= ~DR_TRAP_BITS;
- vcpu->arch.dr6 |= dr6 | DR6_RTM;
- kvm_queue_exception(vcpu, DB_VECTOR);
+ kvm_queue_exception_p(vcpu, DB_VECTOR, dr6);
*r = 1;
return true;
}
--
2.18.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: x86: fix DR6 delivery for emulated hardware breakpoint
2020-05-05 11:34 [PATCH] KVM: x86: fix DR6 delivery for emulated hardware breakpoint Paolo Bonzini
@ 2020-05-05 14:15 ` Peter Xu
2020-05-06 0:33 ` kbuild test robot
1 sibling, 0 replies; 3+ messages in thread
From: Peter Xu @ 2020-05-05 14:15 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: linux-kernel, kvm, jmattson
On Tue, May 05, 2020 at 07:34:49AM -0400, Paolo Bonzini wrote:
> Go through kvm_queue_exception_p so that the payload is correctly delivered
> through the exit qualification, and add a kvm_update_dr6 call to
> kvm_deliver_exception_payload that is needed on AMD.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
I still think we could also change this in handle_exception_nmi() and
handle_dr() as mentioned in the other thread, but no strong opinion:
Reviewed-by: Peter Xu <peterx@redhat.com>
Thanks,
--
Peter Xu
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: x86: fix DR6 delivery for emulated hardware breakpoint
2020-05-05 11:34 [PATCH] KVM: x86: fix DR6 delivery for emulated hardware breakpoint Paolo Bonzini
2020-05-05 14:15 ` Peter Xu
@ 2020-05-06 0:33 ` kbuild test robot
1 sibling, 0 replies; 3+ messages in thread
From: kbuild test robot @ 2020-05-06 0:33 UTC (permalink / raw)
To: Paolo Bonzini, linux-kernel, kvm, jmattson, peterx; +Cc: kbuild-all, jmattson
[-- Attachment #1: Type: text/plain, Size: 3791 bytes --]
Hi Paolo,
I love your patch! Yet something to improve:
[auto build test ERROR on kvm/linux-next]
[also build test ERROR on tip/auto-latest linus/master v5.7-rc4 next-20200505]
[cannot apply to linux/master]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Paolo-Bonzini/KVM-x86-fix-DR6-delivery-for-emulated-hardware-breakpoint/20200506-043817
base: https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
config: i386-allyesconfig (attached as .config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>
All error/warnings (new ones prefixed by >>):
arch/x86/kvm/x86.c: In function 'kvm_deliver_exception_payload':
>> arch/x86/kvm/x86.c:472:3: error: implicit declaration of function 'kvm_update_dr6'; did you mean 'kvm_update_cpuid'? [-Werror=implicit-function-declaration]
kvm_update_dr6(vcpu);
^~~~~~~~~~~~~~
kvm_update_cpuid
arch/x86/kvm/x86.c: At top level:
>> arch/x86/kvm/x86.c:1071:13: warning: conflicting types for 'kvm_update_dr6'
static void kvm_update_dr6(struct kvm_vcpu *vcpu)
^~~~~~~~~~~~~~
>> arch/x86/kvm/x86.c:1071:13: error: static declaration of 'kvm_update_dr6' follows non-static declaration
arch/x86/kvm/x86.c:472:3: note: previous implicit declaration of 'kvm_update_dr6' was here
kvm_update_dr6(vcpu);
^~~~~~~~~~~~~~
cc1: some warnings being treated as errors
vim +472 arch/x86/kvm/x86.c
432
433 void kvm_deliver_exception_payload(struct kvm_vcpu *vcpu)
434 {
435 unsigned nr = vcpu->arch.exception.nr;
436 bool has_payload = vcpu->arch.exception.has_payload;
437 unsigned long payload = vcpu->arch.exception.payload;
438
439 if (!has_payload)
440 return;
441
442 switch (nr) {
443 case DB_VECTOR:
444 /*
445 * "Certain debug exceptions may clear bit 0-3. The
446 * remaining contents of the DR6 register are never
447 * cleared by the processor".
448 */
449 vcpu->arch.dr6 &= ~DR_TRAP_BITS;
450 /*
451 * DR6.RTM is set by all #DB exceptions that don't clear it.
452 */
453 vcpu->arch.dr6 |= DR6_RTM;
454 vcpu->arch.dr6 |= payload;
455 /*
456 * Bit 16 should be set in the payload whenever the #DB
457 * exception should clear DR6.RTM. This makes the payload
458 * compatible with the pending debug exceptions under VMX.
459 * Though not currently documented in the SDM, this also
460 * makes the payload compatible with the exit qualification
461 * for #DB exceptions under VMX.
462 */
463 vcpu->arch.dr6 ^= payload & DR6_RTM;
464
465 /*
466 * The #DB payload is defined as compatible with the 'pending
467 * debug exceptions' field under VMX, not DR6. While bit 12 is
468 * defined in the 'pending debug exceptions' field (enabled
469 * breakpoint), it is reserved and must be zero in DR6.
470 */
471 vcpu->arch.dr6 &= ~BIT(12);
> 472 kvm_update_dr6(vcpu);
473 break;
474 case PF_VECTOR:
475 vcpu->arch.cr2 = payload;
476 break;
477 }
478
479 vcpu->arch.exception.has_payload = false;
480 vcpu->arch.exception.payload = 0;
481 }
482 EXPORT_SYMBOL_GPL(kvm_deliver_exception_payload);
483
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
[-- Attachment #2: .config.gz --]
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2020-05-05 14:15 ` Peter Xu
2020-05-06 0:33 ` kbuild test robot
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