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 <[email protected]> --- v1 -> v2: - Move the setting to emulate.c instead of x86.c - Shorten title --- arch/x86/kvm/emulate.c | 6 +++++- arch/x86/kvm/vmx.c | 3 --- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 630bcb0..4a4555a 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 @@ static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt, 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 @@ static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt, 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; } diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index f7a0a7f..8f731c0 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -5703,9 +5703,6 @@ static int handle_task_switch(struct kvm_vcpu *vcpu) return 0; } - /* clear all local breakpoint enable flags */ - vmcs_writel(GUEST_DR7, vmcs_readl(GUEST_DR7) & ~0x155); - /* * TODO: What about debug traps on tss switch? * Are we supposed to inject them and update dr6? -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
