linux-kernel - [PATCH v4 3/9] iommu/amd: Introduce global variable for storing common EFR and EFR2

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Date:   Wed, 13 Jul 2022 17:56:45 -0500
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     <linux-kernel@...r.kernel.org>, <iommu@...ts.linux.dev>
CC:     <joro@...tes.org>, <robin.murphy@....com>, <vasant.hegde@....com>,
        <ashish.kalra@....com>, <jon.grimm@....com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: [PATCH v4 3/9] iommu/amd: Introduce global variable for storing common EFR and EFR2

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@...tes.org>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....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