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    Subject[PATCH v14 067/113] KVM: TDX: restore user ret MSRs
    Date
    From: Isaku Yamahata <isaku.yamahata@intel.com>

    Several user ret MSRs are clobbered on TD exit. Restore those values on
    TD exit and before returning to ring 3. Because TSX_CTRL requires special
    treat, this patch doesn't address it.

    Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
    Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
    ---
    arch/x86/kvm/vmx/tdx.c | 43 ++++++++++++++++++++++++++++++++++++++++++
    1 file changed, 43 insertions(+)

    diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
    index 2e76671dabcc..5b5c68a1ece4 100644
    --- a/arch/x86/kvm/vmx/tdx.c
    +++ b/arch/x86/kvm/vmx/tdx.c
    @@ -484,6 +484,28 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
    */
    }

    +struct tdx_uret_msr {
    + u32 msr;
    + unsigned int slot;
    + u64 defval;
    +};
    +
    +static struct tdx_uret_msr tdx_uret_msrs[] = {
    + {.msr = MSR_SYSCALL_MASK, .defval = 0x20200 },
    + {.msr = MSR_STAR,},
    + {.msr = MSR_LSTAR,},
    + {.msr = MSR_TSC_AUX,},
    +};
    +
    +static void tdx_user_return_update_cache(void)
    +{
    + int i;
    +
    + for (i = 0; i < ARRAY_SIZE(tdx_uret_msrs); i++)
    + kvm_user_return_update_cache(tdx_uret_msrs[i].slot,
    + tdx_uret_msrs[i].defval);
    +}
    +
    static void tdx_restore_host_xsave_state(struct kvm_vcpu *vcpu)
    {
    struct kvm_tdx *kvm_tdx = to_kvm_tdx(vcpu->kvm);
    @@ -525,6 +547,7 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu)

    tdx_vcpu_enter_exit(vcpu, tdx);

    + tdx_user_return_update_cache();
    tdx_restore_host_xsave_state(vcpu);
    tdx->host_state_need_restore = true;

    @@ -1651,6 +1674,26 @@ int __init tdx_hardware_setup(struct kvm_x86_ops *x86_ops)
    return -EINVAL;
    }

    + for (i = 0; i < ARRAY_SIZE(tdx_uret_msrs); i++) {
    + /*
    + * Here it checks if MSRs (tdx_uret_msrs) can be saved/restored
    + * before returning to user space.
    + *
    + * this_cpu_ptr(user_return_msrs)->registered isn't checked
    + * because the registration is done at vcpu runtime by
    + * kvm_set_user_return_msr().
    + * Here is setting up cpu feature before running vcpu,
    + * registered is already false.
    + */
    + tdx_uret_msrs[i].slot = kvm_find_user_return_msr(tdx_uret_msrs[i].msr);
    + if (tdx_uret_msrs[i].slot == -1) {
    + /* If any MSR isn't supported, it is a KVM bug */
    + pr_err("MSR %x isn't included by kvm_find_user_return_msr\n",
    + tdx_uret_msrs[i].msr);
    + return -EIO;
    + }
    + }
    +
    max_pkgs = topology_max_packages();
    tdx_mng_key_config_lock = kcalloc(max_pkgs, sizeof(*tdx_mng_key_config_lock),
    GFP_KERNEL);
    --
    2.25.1
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