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Message-ID: <20251117184815.1027271-16-smostafa@google.com>
Date: Mon, 17 Nov 2025 18:48:02 +0000
From: Mostafa Saleh <smostafa@...gle.com>
To: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
kvmarm@...ts.linux.dev, iommu@...ts.linux.dev
Cc: catalin.marinas@....com, will@...nel.org, maz@...nel.org,
oliver.upton@...ux.dev, joey.gouly@....com, suzuki.poulose@....com,
yuzenghui@...wei.com, joro@...tes.org, jean-philippe@...aro.org, jgg@...pe.ca,
praan@...gle.com, danielmentz@...gle.com, mark.rutland@....com,
qperret@...gle.com, tabba@...gle.com, Mostafa Saleh <smostafa@...gle.com>
Subject: [PATCH v5 15/27] iommu/arm-smmu-v3-kvm: Create array for hyp SMMUv3
As the hypervisor has no access to firmware tables, the device discovery
is done from the kernel, where it parses firmware tables and populates a
list of devices to the hypervisor, which later takes over.
Signed-off-by: Mostafa Saleh <smostafa@...gle.com>
---
.../iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c | 82 ++++++++++++++++++-
.../iommu/arm/arm-smmu-v3/pkvm/arm_smmu_v3.h | 13 +++
2 files changed, 91 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c
index ca12560639c5..1d72951b7b53 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c
@@ -8,6 +8,7 @@
#include <asm/kvm_pkvm.h>
#include <linux/auxiliary_bus.h>
+#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
@@ -16,6 +17,45 @@
extern struct kvm_iommu_ops kvm_nvhe_sym(smmu_ops);
+static size_t kvm_arm_smmu_count;
+static struct hyp_arm_smmu_v3_device *kvm_arm_smmu_array;
+static size_t kvm_arm_smmu_cur;
+
+static void kvm_arm_smmu_array_free(void)
+{
+ int order;
+
+ order = get_order(kvm_arm_smmu_count * sizeof(*kvm_arm_smmu_array));
+ free_pages((unsigned long)kvm_arm_smmu_array, order);
+}
+
+/*
+ * The hypervisor have to know the basic information about the SMMUs
+ * from the firmware.
+ * This has to be done before the SMMUv3 probes and does anything meaningful
+ * with the hardware, otherwise it becomes harder to reason about the SMMU
+ * state and we'd require to hand-off the state to the hypervisor at certain point
+ * while devices are live, which is complicated and dangerous.
+ * Instead, the hypervisor is interested in a very small part of the probe path,
+ * so just add a separate logic for it.
+ */
+static int kvm_arm_smmu_array_alloc(void)
+{
+ int smmu_order;
+ struct device_node *np;
+
+ for_each_compatible_node(np, NULL, "arm,smmu-v3")
+ kvm_arm_smmu_count++;
+
+ if (!kvm_arm_smmu_count)
+ return -ENODEV;
+ smmu_order = get_order(kvm_arm_smmu_count * sizeof(*kvm_arm_smmu_array));
+ kvm_arm_smmu_array = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, smmu_order);
+ if (!kvm_arm_smmu_array)
+ return -ENOMEM;
+ return 0;
+}
+
static size_t smmu_hyp_pgt_pages(void)
{
/*
@@ -30,6 +70,21 @@ static size_t smmu_hyp_pgt_pages(void)
static struct platform_driver smmuv3_nesting_driver;
static int smmuv3_nesting_probe(struct platform_device *pdev)
{
+ struct resource *res;
+ struct hyp_arm_smmu_v3_device *smmu = &kvm_arm_smmu_array[kvm_arm_smmu_cur];
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ smmu->mmio_addr = res->start;
+ smmu->mmio_size = resource_size(res);
+ if (smmu->mmio_size < SZ_128K) {
+ dev_err(&pdev->dev, "MMIO region too small(%pr)\n", &res);
+ return -EINVAL;
+ }
+
+ if (of_dma_is_coherent(pdev->dev.of_node))
+ smmu->features |= ARM_SMMU_FEAT_COHERENCY;
+
+ kvm_arm_smmu_cur++;
return 0;
}
@@ -41,12 +96,31 @@ static int kvm_arm_smmu_v3_register(void)
if (!is_protected_kvm_enabled() || !nr_pages)
return 0;
- ret = platform_driver_probe(&smmuv3_nesting_driver, smmuv3_nesting_probe);
+ ret = kvm_arm_smmu_array_alloc();
if (ret)
return ret;
- return kvm_iommu_register_driver(kern_hyp_va(lm_alias(&kvm_nvhe_sym(smmu_ops))),
- nr_pages);
+ ret = platform_driver_probe(&smmuv3_nesting_driver, smmuv3_nesting_probe);
+ if (ret)
+ goto out_err;
+
+ ret = kvm_iommu_register_driver(kern_hyp_va(lm_alias(&kvm_nvhe_sym(smmu_ops))),
+ nr_pages);
+ if (ret)
+ goto out_err;
+
+ /*
+ * These variables are stored in the nVHE image, and won't be accessible
+ * after KVM initialization. Ownership of kvm_arm_smmu_array will be
+ * transferred to the hypervisor as well.
+ */
+ kvm_hyp_arm_smmu_v3_smmus = kvm_arm_smmu_array;
+ kvm_hyp_arm_smmu_v3_count = kvm_arm_smmu_count;
+ return ret;
+
+out_err:
+ kvm_arm_smmu_array_free();
+ return ret;
};
static int smmu_create_aux_device(struct device *dev, void *data)
@@ -67,7 +141,7 @@ static int smmu_create_aux_device(struct device *dev, void *data)
static struct platform_driver smmuv3_nesting_driver;
static int kvm_arm_smmu_v3_post_init(void)
{
- if (!is_protected_kvm_enabled())
+ if (!is_protected_kvm_enabled() || !kvm_arm_smmu_cur)
return 0;
WARN_ON(driver_for_each_device(&smmuv3_nesting_driver.driver, NULL,
diff --git a/drivers/iommu/arm/arm-smmu-v3/pkvm/arm_smmu_v3.h b/drivers/iommu/arm/arm-smmu-v3/pkvm/arm_smmu_v3.h
index f6ad91d3fb85..744ee2b7f0b4 100644
--- a/drivers/iommu/arm/arm-smmu-v3/pkvm/arm_smmu_v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/pkvm/arm_smmu_v3.h
@@ -4,7 +4,20 @@
#include <asm/kvm_asm.h>
+/*
+ * Parameters from the trusted host:
+ * @mmio_addr base address of the SMMU registers
+ * @mmio_size size of the registers resource
+ * @features Features of SMMUv3, subset of the main driver
+ *
+ * Other members are filled and used at runtime by the SMMU driver.
+ * @base Virtual address of SMMU registers
+ */
struct hyp_arm_smmu_v3_device {
+ phys_addr_t mmio_addr;
+ size_t mmio_size;
+ void __iomem *base;
+ u32 features;
};
extern size_t kvm_nvhe_sym(kvm_hyp_arm_smmu_v3_count);
--
2.52.0.rc1.455.g30608eb744-goog
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