[RFC PATCH v3 11/11] coco: guest: arm64: Enable vdev DMA after attestation

Aneesh Kumar K.V (Arm)
2026-03-12T08:06:00Z

- define SMC_RSI_VDEV_DMA_ENABLE and add wrapper in rsi_cmds.h
- invoke the new helper from the guest accept path once the device
passes attestation, rolling back to TDI_LOCKED on failure

Cc: Marc Zyngier <maz@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Alexey Kardashevskiy <aik@amd.com>
Cc: Samuel Ortiz <sameo@rivosinc.com>
Cc: Xu Yilun <yilun.xu@linux.intel.com>
Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com>
Cc: Steven Price <steven.price@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
arch/arm64/include/asm/rsi_cmds.h | 16 ++++++++++++++++
arch/arm64/include/asm/rsi_smc.h | 2 ++
drivers/virt/coco/arm-cca-guest/rsi-da.c | 14 ++++++++++++++
3 files changed, 32 insertions(+)

diff --git a/arch/arm64/include/asm/rsi_cmds.h b/arch/arm64/include/asm/rsi_cmds.h
index f72d8e0cd422..1e0d1cd8841a 100644
--- a/arch/arm64/include/asm/rsi_cmds.h
+++ b/arch/arm64/include/asm/rsi_cmds.h
@@ -226,4 +226,20 @@ static inline unsigned long rsi_vdev_get_info(unsigned long vdev_id,
return res.a0;
}

+static inline unsigned long __rsi_vdev_dma_enable(unsigned long vdev_id,
+ unsigned long flags,
+ unsigned long non_ats_plane,
+ unsigned long lock_nonce,
+ unsigned long meas_nonce,
+ unsigned long report_nonce)
+{
+ struct arm_smccc_res res;
+
+ arm_smccc_1_1_invoke(SMC_RSI_VDEV_DMA_ENABLE, vdev_id, flags,
+ non_ats_plane, lock_nonce,
+ meas_nonce, report_nonce, &res);
+
+ return res.a0;
+}
+
#endif /* __ASM_RSI_CMDS_H */
diff --git a/arch/arm64/include/asm/rsi_smc.h b/arch/arm64/include/asm/rsi_smc.h
index 5f1837282237..d2ea3656ea8f 100644
--- a/arch/arm64/include/asm/rsi_smc.h
+++ b/arch/arm64/include/asm/rsi_smc.h
@@ -186,6 +186,8 @@ struct realm_config {
*/
#define SMC_RSI_IPA_STATE_GET SMC_RSI_FID(0x198)

+#define SMC_RSI_VDEV_DMA_ENABLE SMC_RSI_FID(0x19C)
+
struct rsi_vdevice_info {
union {
struct {
diff --git a/drivers/virt/coco/arm-cca-guest/rsi-da.c b/drivers/virt/coco/arm-cca-guest/rsi-da.c
index 4030fa213ff4..74594066f46c 100644
--- a/drivers/virt/coco/arm-cca-guest/rsi-da.c
+++ b/drivers/virt/coco/arm-cca-guest/rsi-da.c
@@ -231,9 +231,17 @@ int cca_verify_digests(u64 hash_algo,
return 0;
}

+static inline int rsi_vdev_enable_dma(int vdev_id, struct dsm_device_info *dev_info)
+{
+ /* No ATS support */
+ return __rsi_vdev_dma_enable(vdev_id, 0, 0, dev_info->lock_nonce,
+ dev_info->meas_nonce, dev_info->report_nonce);
+}
+
int cca_device_accept(struct pci_dev *pdev, unsigned long lock_nonce)
{
int ret;
+ int vdev_id = rsi_vdev_id(pdev);
struct cca_guest_dsc *dsc = to_cca_guest_dsc(pdev);

if (lock_nonce != dsc->dev_info.lock_nonce) {
@@ -270,6 +278,12 @@ int cca_device_accept(struct pci_dev *pdev, unsigned long lock_nonce)
return ret;
}

+ if (rsi_vdev_enable_dma(vdev_id, &dsc->dev_info)) {
+ rhi_vdev_set_tdi_state(pdev, RHI_DA_TDI_CONFIG_LOCKED);
+ pci_err(pdev, "failed to enable DMA from the device\n");
+ return -EIO;
+ }
+
dsc->pci.mmio = no_free_ptr(tsm_mmio);
return 0;
}
--
2.43.0