linux-kernel - [PATCH 5.11 271/775] KVM: x86: Restore all 64 bits of DR6 and DR7 during RSM on x86-64

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Date:   Mon,  1 Mar 2021 17:07:19 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.11 271/775] KVM: x86: Restore all 64 bits of DR6 and DR7 during RSM on x86-64

From: Sean Christopherson <seanjc@...gle.com>

[ Upstream commit 2644312052d54e2e7543c7d186899a36ed22f0bf ]

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: 660a5d517aaa ("KVM: x86: save/load state on SMM switch")
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Message-Id: <20210205012458.3872687-3-seanjc@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/kvm/emulate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 66a08322988f2..1453b9b794425 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -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;
-- 
2.27.0