KVM: x86: Remove misleading DR6/DR7 adjustments from RSM emulation

Drop the DR6/7 volatile+fixed bits adjustments in RSM emulation, which
are redundant and misleading.  The necessary adjustments are made by
kvm_set_dr(), which properly sets the fixed bits that are conditional
on the vCPU model.

Note, KVM incorrectly reads only bits 31:0 of the DR6/7 fields when
emulating RSM on x86-64.  On the plus side for this change, that bug
makes removing "& DRx_VOLATILE" a nop.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210205012458.3872687-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 612ee69..b5f433d 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2506,12 +2506,12 @@ static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt,
 
        val = GET_SMSTATE(u32, smstate, 0x7fcc);
 
-       if (ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1))
+       if (ctxt->ops->set_dr(ctxt, 6, val))
                return X86EMUL_UNHANDLEABLE;
 
        val = GET_SMSTATE(u32, smstate, 0x7fc8);
 
-       if (ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1))
+       if (ctxt->ops->set_dr(ctxt, 7, val))
                return X86EMUL_UNHANDLEABLE;
 
        selector =                 GET_SMSTATE(u32, smstate, 0x7fc4);
@@ -2566,12 +2566,12 @@ static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt,
 
        val = GET_SMSTATE(u32, smstate, 0x7f68);
 
-       if (ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1))
+       if (ctxt->ops->set_dr(ctxt, 6, val))
                return X86EMUL_UNHANDLEABLE;
 
        val = GET_SMSTATE(u32, smstate, 0x7f60);
 
-       if (ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1))
+       if (ctxt->ops->set_dr(ctxt, 7, val))
                return X86EMUL_UNHANDLEABLE;
 
        cr0 =                       GET_SMSTATE(u64, smstate, 0x7f58);