mshv_vtl/tdx: Eliminate possibly duplicate tdg.vp.wr(tsc deadline = disarm)

On timer expire path, it unconditionally issues
tdg.vp.wr(tsc deadline = disarm).  The following tdg.vp.enter() may issue
tdg.vp.wr(new tsc deadline).  The previous disarming is duplicated.  Delete
the duplicated tdg.vp.wr() call as optimization.

Signed-off-by: Isaku Yamahata <[email protected]>

Author: yamahata

drivers/hv/mshv_vtl_main.c

@@ -207,6 +207,7 @@ struct mshv_vtl_per_cpu {
 	u64 l1_msr_tsc_aux;
 	u64 l2_tsc_deadline_prev[MSHV_VTL_NUM_L2_VM];
 	u64 l2_hlt_tsc_deadline;
+	bool l2_tsc_deadline_expired[MSHV_VTL_NUM_L2_VM];
 	bool msrs_are_guest;
 	struct user_return_notifier mshv_urn;
 #endif
@@ -678,6 +679,7 @@ static void mshv_vtl_set_tsc_deadline(u64 vm_idx, u64 deadline)
 
 	tdg_vp_wr(TDVPS_TSC_DEADLINE + vm_idx, deadline, ~0ULL);
 	per_cpu->l2_tsc_deadline_prev[vm_idx - 1] = deadline;
+	per_cpu->l2_tsc_deadline_expired[vm_idx - 1] = false;
 }
 
 #endif
@@ -954,14 +956,18 @@ static void mshv_vtl_return_tdx_tsc_deadline(struct mshv_vtl_run *vtl_run)
 	struct tdx_vp_context *context = &vtl_run->tdx_context;
 	u64 vm_idx, deadline;
 
-	if (!(context->l2_tsc_deadline.update & MSHV_VTL_TDX_L2_DEADLINE_UPDATE))
-		return;
-
 	/* L2 VM index is encoded in entry_rcx for TDG.VP.ENTER(). */
 	vm_idx = TDG_VP_ENTRY_VM_IDX(vtl_run->tdx_context.entry_rcx);
 	if (!is_tdx_vm_idx_valid(vm_idx))
 		return;
 
+	if (!(context->l2_tsc_deadline.update & MSHV_VTL_TDX_L2_DEADLINE_UPDATE)) {
+		if (per_cpu->l2_tsc_deadline_expired[vm_idx - 1])
+			mshv_vtl_set_tsc_deadline(vm_idx, TDVPS_TSC_DEADLINE_DISARMED);
+
+		return;
+	}
+
 	deadline = tsc_deadline_to_tdvps(context->l2_tsc_deadline.deadline);
 	if (deadline != per_cpu->l2_tsc_deadline_prev[vm_idx - 1])
 		mshv_vtl_set_tsc_deadline(vm_idx, deadline);
@@ -978,8 +984,7 @@ static void mshv_tdx_tsc_deadline_expired(struct tdx_vp_context *context)
 	if (!is_tdx_vm_idx_valid(vm_idx))
 		return;
 
-	if (per_cpu->l2_tsc_deadline_prev[vm_idx - 1] != TDVPS_TSC_DEADLINE_DISARMED)
-		mshv_vtl_set_tsc_deadline(vm_idx, TDVPS_TSC_DEADLINE_DISARMED);
+	per_cpu->l2_tsc_deadline_expired[vm_idx - 1] = true;
 }
 
 void mshv_vtl_return_tdx(void)
@@ -1110,7 +1115,8 @@ static enum TDX_HALT_TIMER mshv_tdx_setup_halt_timer(void)
 		struct mshv_vtl_per_cpu *per_cpu = this_cpu_ptr(&mshv_vtl_per_cpu);
 		u64 vm_idx = TDG_VP_ENTRY_VM_IDX(context->entry_rcx);
 
-		if (is_tdx_vm_idx_valid(vm_idx))
+		if (is_tdx_vm_idx_valid(vm_idx) &&
+		    !per_cpu->l2_tsc_deadline_expired[vm_idx - 1])
 			deadline = per_cpu->l2_tsc_deadline_prev[vm_idx - 1];
 	}
 #endif