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From:   Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
To:     <linux-kernel@vger.kernel.org>, <iommu@lists.linux.dev>
CC:     <joro@8bytes.org>, <robin.murphy@arm.com>, <vasant.hegde@amd.com>,
        <ashish.kalra@amd.com>, <jon.grimm@amd.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Subject: [PATCH v4 3/9] iommu/amd: Introduce global variable for storing common EFR and EFR2
Date:   Wed, 13 Jul 2022 17:56:45 -0500
Message-ID: <20220713225651.20758-4-suravee.suthikulpanit@amd.com>
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Some IOMMU features require that all IOMMUs must support the feature,
which is determined by checking the support bit in the Extended Feature
Register 1 and 2 (EFR/EFR2) on all IOMMUs. This check is done by the
function check_feature_on_all_iommus(), which iterates through all
IOMMUs everytime it is called.

Instead, introduce a global variable to store common EFR/EFR2 among all
IOMMUs. In case of inconsistent EFR/EFR2 masks are detected on an IOMMU,
a FW_BUG warning is reported.

Suggested-by: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/amd_iommu.h |  3 +++
 drivers/iommu/amd/init.c      | 45 ++++++++++++++++++++++++++++-------
 2 files changed, 40 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/amd/amd_iommu.h b/drivers/iommu/amd/amd_iommu.h
index 9b7092182ca7..1b945d47741c 100644
--- a/drivers/iommu/amd/amd_iommu.h
+++ b/drivers/iommu/amd/amd_iommu.h
@@ -137,4 +137,7 @@ static inline void amd_iommu_apply_ivrs_quirks(void) { }
 extern void amd_iommu_domain_set_pgtable(struct protection_domain *domain,
 					 u64 *root, int mode);
 extern struct dev_table_entry *get_dev_table(struct amd_iommu *iommu);
+
+extern u64 amd_iommu_efr;
+extern u64 amd_iommu_efr2;
 #endif
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 92ab02f6c5dc..741fee1abfc4 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -164,6 +164,10 @@ static bool amd_iommu_disabled __initdata;
 static bool amd_iommu_force_enable __initdata;
 static int amd_iommu_target_ivhd_type;
 
+/* Global EFR and EFR2 registers */
+u64 amd_iommu_efr;
+u64 amd_iommu_efr2;
+
 LIST_HEAD(amd_iommu_pci_seg_list);	/* list of all PCI segments */
 LIST_HEAD(amd_iommu_list);		/* list of all AMD IOMMUs in the
 					   system */
@@ -259,21 +263,46 @@ int amd_iommu_get_num_iommus(void)
 	return amd_iommus_present;
 }
 
-#ifdef CONFIG_IRQ_REMAP
-static bool check_feature_on_all_iommus(u64 mask)
+/*
+ * Iterate through all the IOMMUs to get common EFR
+ * masks among all IOMMUs and warn if found inconsistency.
+ */
+static void get_global_efr(void)
 {
-	bool ret = false;
 	struct amd_iommu *iommu;
 
 	for_each_iommu(iommu) {
-		ret = iommu_feature(iommu, mask);
-		if (!ret)
-			return false;
+		u64 tmp = iommu->features;
+		u64 tmp2 = iommu->features2;
+
+		if (list_is_first(&iommu->list, &amd_iommu_list)) {
+			amd_iommu_efr = tmp;
+			amd_iommu_efr2 = tmp2;
+			continue;
+		}
+
+		if (amd_iommu_efr == tmp &&
+		    amd_iommu_efr2 == tmp2)
+			continue;
+
+		pr_err(FW_BUG
+		       "Found inconsistent EFR/EFR2 %#llx,%#llx (global %#llx,%#llx) on iommu%d (%04x:%02x:%02x.%01x).\n",
+		       tmp, tmp2, amd_iommu_efr, amd_iommu_efr2,
+		       iommu->index, iommu->pci_seg->id,
+		       PCI_BUS_NUM(iommu->devid), PCI_SLOT(iommu->devid),
+		       PCI_FUNC(iommu->devid));
+
+		amd_iommu_efr &= tmp;
+		amd_iommu_efr2 &= tmp2;
 	}
 
-	return true;
+	pr_info("Using global IVHD EFR:%#llx, EFR2:%#llx\n", amd_iommu_efr, amd_iommu_efr2);
+}
+
+static bool check_feature_on_all_iommus(u64 mask)
+{
+	return !!(amd_iommu_efr & mask);
 }
-#endif
 
 /*
  * For IVHD type 0x11/0x40, EFR is also available via IVHD.
-- 
2.32.0