On 2/26/2024 4:26 PM, isaku.yamahata@xxxxxxxxx wrote:
From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
Several user ret MSRs are clobbered on TD exit. Restore those values on
TD exit
Here "Restore" is not accurate, since the previous patch just updates
the cached value 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@xxxxxxxxx>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
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 199226c6cf55..7e2b1e554246 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -535,6 +535,28 @@ 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);
@@ -627,6 +649,7 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu)
tdx_vcpu_enter_exit(tdx);
+ tdx_user_return_update_cache();
tdx_restore_host_xsave_state(vcpu);
tdx->host_state_need_restore = true;
@@ -1972,6 +1995,26 @@ 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().
Should be tdx_user_return_update_cache(), if it's the final API name.
+ * Here is setting up cpu feature before running vcpu,
+ * registered is already false.
^
remove "already"?
+ */
+ 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);
