powerpc fixes for 5.15 #4

Fix a bug where guests on P9 with interrupts passed through could get stuck in
 synchronize_irq().
 
 Fix a bug in KVM on P8 where secondary threads entering a guest would write outside their
 allocated stack.
 
 Fix a bug in KVM on P8 where secondary threads could confuse the host offline code and
 cause the guest or host to crash.
 
 Thanks to: Cédric Le Goater
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Merge tag 'powerpc-5.15-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:

 - Fix a bug where guests on P9 with interrupts passed through could get
   stuck in synchronize_irq().

 - Fix a bug in KVM on P8 where secondary threads entering a guest would
   write outside their allocated stack.

 - Fix a bug in KVM on P8 where secondary threads could confuse the host
   offline code and cause the guest or host to crash.

Thanks to Cédric Le Goater.

* tag 'powerpc-5.15-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  KVM: PPC: Book3S HV: Make idle_kvm_start_guest() return 0 if it went to guest
  KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest()
  powerpc/xive: Discard disabled interrupts in get_irqchip_state()

arch/powerpc/kvm/book3s_hv_rmhandlers.S

@@ -255,13 +255,16 @@ kvm_novcpu_exit:
  * r3 contains the SRR1 wakeup value, SRR1 is trashed.
  */
 _GLOBAL(idle_kvm_start_guest)
-	ld	r4,PACAEMERGSP(r13)
 	mfcr	r5
 	mflr	r0
-	std	r1,0(r4)
-	std	r5,8(r4)
-	std	r0,16(r4)
-	subi	r1,r4,STACK_FRAME_OVERHEAD
+	std	r5, 8(r1)	// Save CR in caller's frame
+	std	r0, 16(r1)	// Save LR in caller's frame
+	// Create frame on emergency stack
+	ld	r4, PACAEMERGSP(r13)
+	stdu	r1, -SWITCH_FRAME_SIZE(r4)
+	// Switch to new frame on emergency stack
+	mr	r1, r4
+	std	r3, 32(r1)	// Save SRR1 wakeup value
 	SAVE_NVGPRS(r1)
 
 	/*
@@ -313,6 +316,10 @@ kvm_unsplit_wakeup:
 
 kvm_secondary_got_guest:
 
+	// About to go to guest, clear saved SRR1
+	li	r0, 0
+	std	r0, 32(r1)
+
 	/* Set HSTATE_DSCR(r13) to something sensible */
 	ld	r6, PACA_DSCR_DEFAULT(r13)
 	std	r6, HSTATE_DSCR(r13)
@@ -392,13 +399,12 @@ kvm_no_guest:
 	mfspr	r4, SPRN_LPCR
 	rlwimi	r4, r3, 0, LPCR_PECE0 | LPCR_PECE1
 	mtspr	SPRN_LPCR, r4
-	/* set up r3 for return */
-	mfspr	r3,SPRN_SRR1
+	// Return SRR1 wakeup value, or 0 if we went into the guest
+	ld	r3, 32(r1)
 	REST_NVGPRS(r1)
-	addi	r1, r1, STACK_FRAME_OVERHEAD
-	ld	r0, 16(r1)
-	ld	r5, 8(r1)
-	ld	r1, 0(r1)
+	ld	r1, 0(r1)	// Switch back to caller stack
+	ld	r0, 16(r1)	// Reload LR
+	ld	r5, 8(r1)	// Reload CR
 	mtlr	r0
 	mtcr	r5
 	blr

arch/powerpc/sysdev/xive/common.c

@@ -945,7 +945,8 @@ static int xive_get_irqchip_state(struct irq_data *data,
 		 * interrupt to be inactive in that case.
 		 */
 		*state = (pq != XIVE_ESB_INVALID) && !xd->stale_p &&
-			(xd->saved_p || !!(pq & XIVE_ESB_VAL_P));
+			(xd->saved_p || (!!(pq & XIVE_ESB_VAL_P) &&
+			 !irqd_irq_disabled(data)));
 		return 0;
 	default:
 		return -EINVAL;