s390/pci: improve irq number check for msix

s390s arch_setup_msi_irqs function ensures that we don't return with
more irqs than the PCI architecture allows and that a single PCI
function doesn't consume more irqs than the kernel is configured for.

At least the last check doesn't help much and should take the sum of
all irqs into account. Since that's already done by irq_alloc_desc
we can remove this check.

As for the first check we should use the value provided by the
firmware which can be less than what the PCI architecture allows.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/pci.h

@@ -50,10 +50,6 @@ struct zpci_fmb {
 	atomic64_t unmapped_pages;
 } __packed __aligned(16);
 
-#define ZPCI_MSI_VEC_BITS	11
-#define ZPCI_MSI_VEC_MAX	(1 << ZPCI_MSI_VEC_BITS)
-#define ZPCI_MSI_VEC_MASK	(ZPCI_MSI_VEC_MAX - 1)
-
 enum zpci_state {
 	ZPCI_FN_STATE_RESERVED,
 	ZPCI_FN_STATE_STANDBY,
@@ -90,6 +86,7 @@ struct zpci_dev {
 
 	/* IRQ stuff */
 	u64		msi_addr;	/* MSI address */
+	unsigned int	max_msi;	/* maximum number of MSI's */
 	struct airq_iv *aibv;		/* adapter interrupt bit vector */
 	unsigned int	aisb;		/* number of the summary bit */
 

arch/s390/pci/pci.c

@@ -369,8 +369,7 @@ int arch_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
 
 	if (type == PCI_CAP_ID_MSI && nvec > 1)
 		return 1;
-	msi_vecs = min(nvec, ZPCI_MSI_VEC_MAX);
-	msi_vecs = min_t(unsigned int, msi_vecs, CONFIG_PCI_NR_MSI);
+	msi_vecs = min_t(unsigned int, nvec, zdev->max_msi);
 
 	/* Allocate adapter summary indicator bit */
 	rc = -EIO;

arch/s390/pci/pci_clp.c

@@ -62,6 +62,7 @@ static void clp_store_query_pci_fngrp(struct zpci_dev *zdev,
 	zdev->tlb_refresh = response->refresh;
 	zdev->dma_mask = response->dasm;
 	zdev->msi_addr = response->msia;
+	zdev->max_msi = response->noi;
 	zdev->fmb_update = response->mui;
 
 	switch (response->version) {