powerpc: Enable support for 32 bit MSI-X vectors

Some devices are not capable of addressing 64 bits
via DMA, which includes MSI-X vectors. This allows
us to ensure these devices use MSI-X vectors in
32 bit space.
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240117214632.134539-1-brking@linux.vnet.ibm.com

arch/powerpc/platforms/pseries/msi.c

@@ -26,6 +26,7 @@ static int query_token, change_token;
 #define RTAS_CHANGE_MSI_FN	3
 #define RTAS_CHANGE_MSIX_FN	4
 #define RTAS_CHANGE_32MSI_FN	5
+#define RTAS_CHANGE_32MSIX_FN	6
 
 /* RTAS Helpers */
 
@@ -41,7 +42,7 @@ static int rtas_change_msi(struct pci_dn *pdn, u32 func, u32 num_irqs)
 	seq_num = 1;
 	do {
 		if (func == RTAS_CHANGE_MSI_FN || func == RTAS_CHANGE_MSIX_FN ||
-		    func == RTAS_CHANGE_32MSI_FN)
+		    func == RTAS_CHANGE_32MSI_FN || func == RTAS_CHANGE_32MSIX_FN)
 			rc = rtas_call(change_token, 6, 4, rtas_ret, addr,
 					BUID_HI(buid), BUID_LO(buid),
 					func, num_irqs, seq_num);
@@ -406,8 +407,12 @@ static int rtas_prepare_msi_irqs(struct pci_dev *pdev, int nvec_in, int type,
 
 		if (use_32bit_msi_hack && rc > 0)
 			rtas_hack_32bit_msi_gen2(pdev);
-	} else
-		rc = rtas_change_msi(pdn, RTAS_CHANGE_MSIX_FN, nvec);
+	} else {
+		if (pdev->no_64bit_msi)
+			rc = rtas_change_msi(pdn, RTAS_CHANGE_32MSIX_FN, nvec);
+		else
+			rc = rtas_change_msi(pdn, RTAS_CHANGE_MSIX_FN, nvec);
+	}
 
 	if (rc != nvec) {
 		if (nvec != nvec_in) {