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[Qemu-devel] [PULL 16/25] target/i386: kvm: Re-inject #DB to guest with
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 16/25] target/i386: kvm: Re-inject #DB to guest with updated DR6 |
Date: |
Fri, 21 Jun 2019 13:30:11 +0200 |
From: Liran Alon <address@hidden>
If userspace (QEMU) debug guest, when #DB is raised in guest and
intercepted by KVM, KVM forwards information on #DB to userspace
instead of injecting #DB to guest.
While doing so, KVM don't update vCPU DR6 but instead report the #DB DR6
value to userspace for further handling.
See KVM's handle_exception() DB_VECTOR handler.
QEMU handler for this case is kvm_handle_debug(). This handler basically
checks if #DB is related to one of user set hardware breakpoints and if
not, it re-inject #DB into guest.
The re-injection is done by setting env->exception_injected to #DB which
will later be passed as events.exception.nr to KVM_SET_VCPU_EVENTS ioctl
by kvm_put_vcpu_events().
However, in case userspace re-injects #DB, KVM expects userspace to set
vCPU DR6 as reported to userspace when #DB was intercepted! Otherwise,
KVM_REQ_EVENT handler will inject #DB with wrong DR6 to guest.
Fix this issue by updating vCPU DR6 appropriately when re-inject #DB to
guest.
Reviewed-by: Nikita Leshenko <address@hidden>
Reviewed-by: Krish Sadhukhan <address@hidden>
Signed-off-by: Liran Alon <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
target/i386/kvm.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index c763643..9864aa0 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -3897,6 +3897,9 @@ static int kvm_handle_debug(X86CPU *cpu,
/* pass to guest */
env->exception_injected = arch_info->exception;
env->has_error_code = 0;
+ if (arch_info->exception == EXCP01_DB) {
+ env->dr[6] = arch_info->dr6;
+ }
}
return ret;
--
1.8.3.1
- [Qemu-devel] [PULL v2 00/25] Misc (mostly x86) patches for 2019-06-21, Paolo Bonzini, 2019/06/21
- [Qemu-devel] [PULL 03/25] i386/kvm: convert hyperv enlightenments properties from bools to bits, Paolo Bonzini, 2019/06/21
- [Qemu-devel] [PULL 04/25] i386/kvm: add support for KVM_GET_SUPPORTED_HV_CPUID, Paolo Bonzini, 2019/06/21
- [Qemu-devel] [PULL 01/25] kvm-all: Add/update fprintf's for kvm_*_ioeventfd_del, Paolo Bonzini, 2019/06/21
- [Qemu-devel] [PULL 02/25] hax: Honor CPUState::halted, Paolo Bonzini, 2019/06/21
- [Qemu-devel] [PULL 06/25] i386/kvm: document existing Hyper-V enlightenments, Paolo Bonzini, 2019/06/21
- [Qemu-devel] [PULL 10/25] i386/kvm: hv-evmcs requires hv-vapic, Paolo Bonzini, 2019/06/21
- [Qemu-devel] [PULL 14/25] KVM: Introduce kvm_arch_destroy_vcpu(), Paolo Bonzini, 2019/06/21
- [Qemu-devel] [PULL 15/25] target/i386: kvm: Use symbolic constant for #DB/#BP exception constants, Paolo Bonzini, 2019/06/21
- [Qemu-devel] [PULL 05/25] i386/kvm: move Hyper-V CPUID filling to hyperv_handle_properties(), Paolo Bonzini, 2019/06/21
- [Qemu-devel] [PULL 16/25] target/i386: kvm: Re-inject #DB to guest with updated DR6,
Paolo Bonzini <=
- [Qemu-devel] [PULL 22/25] target/i386: kvm: Add nested migration blocker only when kernel lacks required capabilities, Paolo Bonzini, 2019/06/21
[Qemu-devel] [PULL 19/25] vmstate: Add support for kernel integer types, Paolo Bonzini, 2019/06/21
[Qemu-devel] [PULL 09/25] i386/kvm: hv-tlbflush/ipi require hv-vpindex, Paolo Bonzini, 2019/06/21
[Qemu-devel] [PULL 07/25] i386/kvm: implement 'hv-passthrough' mode, Paolo Bonzini, 2019/06/21
[Qemu-devel] [PULL 08/25] i386/kvm: hv-stimer requires hv-time and hv-synic, Paolo Bonzini, 2019/06/21