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    Subject[PATCH 2/9] KVM: SVM: Add checks for CRx read and write intercepts
    Date
    This patch add code to check for any CRx read, write, and
    the selective-cr0 intercepts for instructions emulated in
    software by KVM.

    Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
    ---
    arch/x86/kvm/svm.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++-
    1 files changed, 72 insertions(+), 1 deletions(-)

    diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
    index d1721c2..29f0491 100644
    --- a/arch/x86/kvm/svm.c
    +++ b/arch/x86/kvm/svm.c
    @@ -3622,7 +3622,78 @@ static void svm_fpu_deactivate(struct kvm_vcpu *vcpu)
    static int svm_insn_intercepted(struct kvm_vcpu *vcpu,
    struct x86_emulate_ctxt *ctxt)
    {
    - return X86EMUL_CONTINUE;
    + struct decode_cache *c = &ctxt->decode;
    + struct vcpu_svm *svm = to_svm(vcpu);
    + struct vmcb *vmcb = svm->vmcb;
    + int vmexit, ret;
    +
    + if (!is_nested(svm))
    + return X86EMUL_CONTINUE;
    +
    + ret = X86EMUL_CONTINUE;
    +
    + if (!c->twobyte)
    + goto out;
    +
    + switch (c->b) {
    + case 0x01:
    + /* 0x0f 0x01 and modrm_mod == 3 encodes special instructions */
    + if (c->modrm_mod == 3)
    + break;
    +
    + switch (c->modrm_reg) {
    + case 0x04: /* SMSW */
    + vmcb->control.exit_code = SVM_EXIT_READ_CR0;
    + break;
    + case 0x06: { /* LMSW */
    + u64 cr0, val;
    +
    + vmcb->control.exit_code = SVM_EXIT_WRITE_CR0;
    +
    + if (svm->nested.intercept_cr_write & INTERCEPT_CR0_MASK)
    + break;
    +
    + /* check for selective-cr0 special case */
    + cr0 = vcpu->arch.cr0 & ~SVM_CR0_SELECTIVE_MASK & 0xf;
    + val = c->src.val & ~SVM_CR0_SELECTIVE_MASK & 0xf;
    +
    + if (cr0 ^ val)
    + vmcb->control.exit_code = SVM_EXIT_CR0_SEL_WRITE;
    +
    + break;
    + }
    + }
    + case 0x06: /* CLTS */
    + vmcb->control.exit_code = SVM_EXIT_WRITE_CR0;
    + break;
    + case 0x20: /* CR read */
    + vmcb->control.exit_code = SVM_EXIT_READ_CR0 + c->modrm_reg;
    + break;
    + case 0x22: /* CR write */
    + vmcb->control.exit_code = SVM_EXIT_WRITE_CR0 + c->modrm_reg;
    + if (c->modrm_reg == 0 &&
    + !(svm->nested.intercept_cr_write & INTERCEPT_CR0_MASK)) {
    + /* check for selective-cr0 special case */
    + u64 cr0, val;
    +
    + cr0 = vcpu->arch.cr0 & ~SVM_CR0_SELECTIVE_MASK;
    + val = c->src.val & ~SVM_CR0_SELECTIVE_MASK;
    +
    + if (cr0 ^ val)
    + vmcb->control.exit_code = SVM_EXIT_CR0_SEL_WRITE;
    + }
    + break;
    + }
    +
    + vmcb->control.next_rip = ctxt->eip;
    + vmexit = nested_svm_exit_handled(svm);
    +
    + ret = (vmexit == NESTED_EXIT_DONE) ? X86EMUL_INTERCEPTED
    + : X86EMUL_CONTINUE;
    +
    +out:
    +
    + return ret;
    }

    static struct kvm_x86_ops svm_x86_ops = {
    --
    1.7.1



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