KVM: x86: Fix DR7 mask on task-switch while debugging
If the host sets hardware breakpoints to debug the guest, and a task-switch
occurs in the guest, the architectural DR7 will not be updated. The effective
DR7 would be updated instead.
This fix puts the DR7 update during task-switch emulation, so it now uses the
standard DR setting mechanism instead of the one that was previously used. As a
bonus, the update of DR7 will now be effective for AMD as well.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 5839fc5..b32a38e 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -25,6 +25,7 @@
#include <linux/module.h>
#include <asm/kvm_emulate.h>
#include <linux/stringify.h>
+#include <asm/debugreg.h>
#include "x86.h"
#include "tss.h"
@@ -2849,7 +2850,7 @@
ulong old_tss_base =
ops->get_cached_segment_base(ctxt, VCPU_SREG_TR);
u32 desc_limit;
- ulong desc_addr;
+ ulong desc_addr, dr7;
/* FIXME: old_tss_base == ~0 ? */
@@ -2934,6 +2935,9 @@
ret = em_push(ctxt);
}
+ ops->get_dr(ctxt, 7, &dr7);
+ ops->set_dr(ctxt, 7, dr7 & ~(DR_LOCAL_ENABLE_MASK | DR_LOCAL_SLOWDOWN));
+
return ret;
}