From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: peterx@redhat.com
Subject: [PATCH] KVM: x86: pass correct DR6 for GD userspace exit
Date: Wed, 6 May 2020 06:00:14 -0400 [thread overview]
Message-ID: <20200506100014.7451-1-pbonzini@redhat.com> (raw)
When KVM_EXIT_DEBUG is raised for the disabled-breakpoints case (DR7.GD),
DR6 was incorrectly copied from the value in the VM. Instead,
DR6.BD should be set in order to catch this case.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx/vmx.c | 2 +-
.../testing/selftests/kvm/x86_64/debug_regs.c | 24 ++++++++++++++++++-
2 files changed, 24 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 2384a2dbec44..ce534336c115 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4927,7 +4927,7 @@ static int handle_dr(struct kvm_vcpu *vcpu)
* guest debugging itself.
*/
if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) {
- vcpu->run->debug.arch.dr6 = vcpu->arch.dr6;
+ vcpu->run->debug.arch.dr6 = DR6_BD | DR6_RTM | DR6_FIXED_1;
vcpu->run->debug.arch.dr7 = dr7;
vcpu->run->debug.arch.pc = kvm_get_linear_rip(vcpu);
vcpu->run->debug.arch.exception = DB_VECTOR;
diff --git a/tools/testing/selftests/kvm/x86_64/debug_regs.c b/tools/testing/selftests/kvm/x86_64/debug_regs.c
index 2b7187db061d..ed94c0b3da35 100644
--- a/tools/testing/selftests/kvm/x86_64/debug_regs.c
+++ b/tools/testing/selftests/kvm/x86_64/debug_regs.c
@@ -11,10 +11,13 @@
#define VCPU_ID 0
+#define DR6_BD (1 << 13)
+#define DR7_GD (1 << 13)
+
/* For testing data access debug BP */
uint32_t guest_value;
-extern unsigned char sw_bp, hw_bp, write_data, ss_start;
+extern unsigned char sw_bp, hw_bp, write_data, ss_start, bd_start;
static void guest_code(void)
{
@@ -43,6 +46,8 @@ static void guest_code(void)
"rdmsr\n\t"
: : : "rax", "ecx");
+ /* DR6.BD test */
+ asm volatile("bd_start: mov %%dr0, %%rax" : : : "rax");
GUEST_DONE();
}
@@ -165,6 +170,23 @@ int main(void)
target_dr6);
}
+ /* Disable all debug controls, run to the end */
+ CLEAR_DEBUG();
+ debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP;
+ debug.arch.debugreg[7] = 0x400 | DR7_GD;
+ APPLY_DEBUG();
+ vcpu_run(vm, VCPU_ID);
+ target_dr6 = 0xffff0ff0 | DR6_BD;
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG &&
+ run->debug.arch.exception == DB_VECTOR &&
+ run->debug.arch.pc == CAST_TO_RIP(bd_start) &&
+ run->debug.arch.dr6 == target_dr6,
+ "DR7.GD: exit %d exception %d rip 0x%llx "
+ "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)",
+ run->exit_reason, run->debug.arch.exception,
+ run->debug.arch.pc, target_rip, run->debug.arch.dr6,
+ target_dr6);
+
/* Disable all debug controls, run to the end */
CLEAR_DEBUG();
APPLY_DEBUG();
--
2.18.2
reply other threads:[~2020-05-06 10:00 UTC|newest]
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