[PATCH 4.19 53/58] KVM: SVM: Truncate GPR value for DR and CR accesses in !64-bit mode

Greg Kroah-Hartman
2021-06-08T18:42:15Z

From: Sean Christopherson <seanjc@google.com>

commit 0884335a2e653b8a045083aa1d57ce74269ac81d upstream.

Drop bits 63:32 on loads/stores to/from DRs and CRs when the vCPU is not
in 64-bit mode. The APM states bits 63:32 are dropped for both DRs and
CRs:

In 64-bit mode, the operand size is fixed at 64 bits without the need
for a REX prefix. In non-64-bit mode, the operand size is fixed at 32
bits and the upper 32 bits of the destination are forced to 0.

Fixes: 7ff76d58a9dc ("KVM: SVM: enhance MOV CR intercept handler")
Fixes: cae3797a4639 ("KVM: SVM: enhance mov DR intercept handler")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210422022128.3464144-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[sudip: manual backport to old file]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kvm/svm.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4033,7 +4033,7 @@ static int cr_interception(struct vcpu_s
err = 0;
if (cr >= 16) { /* mov to cr */
cr -= 16;
- val = kvm_register_read(&svm->vcpu, reg);
+ val = kvm_register_readl(&svm->vcpu, reg);
switch (cr) {
case 0:
if (!check_selective_cr0_intercepted(svm, val))
@@ -4078,7 +4078,7 @@ static int cr_interception(struct vcpu_s
kvm_queue_exception(&svm->vcpu, UD_VECTOR);
return 1;
}
- kvm_register_write(&svm->vcpu, reg, val);
+ kvm_register_writel(&svm->vcpu, reg, val);
}
return kvm_complete_insn_gp(&svm->vcpu, err);
}
@@ -4108,13 +4108,13 @@ static int dr_interception(struct vcpu_s
if (dr >= 16) { /* mov to DRn */
if (!kvm_require_dr(&svm->vcpu, dr - 16))
return 1;
- val = kvm_register_read(&svm->vcpu, reg);
+ val = kvm_register_readl(&svm->vcpu, reg);
kvm_set_dr(&svm->vcpu, dr - 16, val);
} else {
if (!kvm_require_dr(&svm->vcpu, dr))
return 1;
kvm_get_dr(&svm->vcpu, dr, &val);
- kvm_register_write(&svm->vcpu, reg, val);
+ kvm_register_writel(&svm->vcpu, reg, val);
}

return kvm_skip_emulated_instruction(&svm->vcpu);