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KVM: x86: Restore all 64 bits of DR6 and DR7 during RSM on x86-64

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[ Upstream commit 2644312052 ]

Restore the full 64-bit values of DR6 and DR7 when emulating RSM on
x86-64, as defined by both Intel's SDM and AMD's APM.

Note, bits 63:32 of DR6 and DR7 are reserved, so this is a glorified nop
unless the SMM handler is poking into SMRAM, which it most definitely
shouldn't be doing since both Intel and AMD list the DR6 and DR7 fields
as read-only.

Fixes: 660a5d517a ("KVM: x86: save/load state on SMM switch")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210205012458.3872687-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Sean Christopherson 2021-02-04 17:24:58 -08:00 committed by Greg Kroah-Hartman
parent 6a402b937e
commit 689ceaad94
1 changed files with 2 additions and 2 deletions
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4
arch/x86/kvm/emulate.c
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@ -2564,12 +2564,12 @@ static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt,
ctxt->_eip = GET_SMSTATE(u64, smstate, 0x7f78);
ctxt->eflags = GET_SMSTATE(u32, smstate, 0x7f70) | X86_EFLAGS_FIXED;
val = GET_SMSTATE(u32, smstate, 0x7f68);
val = GET_SMSTATE(u64, smstate, 0x7f68);
if (ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1))
return X86EMUL_UNHANDLEABLE;
val = GET_SMSTATE(u32, smstate, 0x7f60);
val = GET_SMSTATE(u64, smstate, 0x7f60);
if (ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1))
return X86EMUL_UNHANDLEABLE;