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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>
This commit is contained in:
Sean Christopherson 2021-02-04 17:24:57 -08:00 committed by Paolo Bonzini
parent 448841f0b7
commit 16d5163f33
1 changed files with 4 additions and 4 deletions
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8
arch/x86/kvm/emulate.c
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@ -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);