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Message-ID: <20251027094916.1153143-12-aneesh.kumar@kernel.org>
Date: Mon, 27 Oct 2025 15:19:03 +0530
From: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@...nel.org>
To: linux-coco@...ts.linux.dev,
kvmarm@...ts.linux.dev
Cc: linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org,
dan.j.williams@...el.com,
aik@....com,
lukas@...ner.de,
Samuel Ortiz <sameo@...osinc.com>,
Xu Yilun <yilun.xu@...ux.intel.com>,
Jason Gunthorpe <jgg@...pe.ca>,
Suzuki K Poulose <Suzuki.Poulose@....com>,
Steven Price <steven.price@....com>,
Bjorn Helgaas <helgaas@...nel.org>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
Catalin Marinas <catalin.marinas@....com>,
Marc Zyngier <maz@...nel.org>,
Will Deacon <will@...nel.org>,
Oliver Upton <oliver.upton@...ux.dev>,
"Aneesh Kumar K.V (Arm)" <aneesh.kumar@...nel.org>
Subject: [PATCH 12/12] coco: host: arm64: Register device public key with RMM
- Introduce the SMC_RMI_PDEV_SET_PUBKEY helper and the associated struct
rmi_public_key_params so the host can hand the device’s public key to
the RMM.
- Parse the certificate chain cached during IDE setup, extract the final
certificate’s public key, and recognise RSA-3072, ECDSA-P256, and
ECDSA-P384 keys before calling into the RMM.
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@...nel.org>
---
arch/arm64/include/asm/rmi_cmds.h | 9 ++
arch/arm64/include/asm/rmi_smc.h | 18 +++
drivers/virt/coco/arm-cca-host/Kconfig | 4 +
drivers/virt/coco/arm-cca-host/rmi-da.c | 166 +++++++++++++++++++++++-
drivers/virt/coco/arm-cca-host/rmi-da.h | 1 +
5 files changed, 197 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/rmi_cmds.h b/arch/arm64/include/asm/rmi_cmds.h
index f10a0dcaa308..339bea517760 100644
--- a/arch/arm64/include/asm/rmi_cmds.h
+++ b/arch/arm64/include/asm/rmi_cmds.h
@@ -574,4 +574,13 @@ static inline unsigned long rmi_pdev_destroy(unsigned long pdev_phys)
return res.a0;
}
+static inline unsigned long rmi_pdev_set_pubkey(unsigned long pdev_phys, unsigned long key_phys)
+{
+ struct arm_smccc_res res;
+
+ arm_smccc_1_1_invoke(SMC_RMI_PDEV_SET_PUBKEY, pdev_phys, key_phys, &res);
+
+ return res.a0;
+}
+
#endif /* __ASM_RMI_CMDS_H */
diff --git a/arch/arm64/include/asm/rmi_smc.h b/arch/arm64/include/asm/rmi_smc.h
index 6eb6f7e4b77f..1f46e13b92a4 100644
--- a/arch/arm64/include/asm/rmi_smc.h
+++ b/arch/arm64/include/asm/rmi_smc.h
@@ -52,6 +52,7 @@
#define SMC_RMI_PDEV_CREATE SMC_RMI_CALL(0x0176)
#define SMC_RMI_PDEV_DESTROY SMC_RMI_CALL(0x0177)
#define SMC_RMI_PDEV_GET_STATE SMC_RMI_CALL(0x0178)
+#define SMC_RMI_PDEV_SET_PUBKEY SMC_RMI_CALL(0x017b)
#define SMC_RMI_PDEV_STOP SMC_RMI_CALL(0x017c)
#define RMI_ABI_MAJOR_VERSION 1
@@ -426,4 +427,21 @@ struct rmi_dev_comm_data {
};
};
+#define RMI_SIG_RSASSA_3072 0
+#define RMI_SIG_ECDSA_P256 1
+#define RMI_SIG_ECDSA_P384 2
+
+struct rmi_public_key_params {
+ union {
+ struct {
+ u8 public_key[1024];
+ u8 metadata[1024];
+ u64 public_key_len;
+ u64 metadata_len;
+ u8 rmi_signature_algorithm;
+ } __packed;
+ u8 padding[0x1000];
+ };
+};
+
#endif /* __ASM_RMI_SMC_H */
diff --git a/drivers/virt/coco/arm-cca-host/Kconfig b/drivers/virt/coco/arm-cca-host/Kconfig
index 1febd316fb77..efa66e960ad5 100644
--- a/drivers/virt/coco/arm-cca-host/Kconfig
+++ b/drivers/virt/coco/arm-cca-host/Kconfig
@@ -7,8 +7,12 @@ config ARM_CCA_HOST
depends on ARM64
depends on PCI_TSM
depends on KVM
+ select KEYS
+ select X509_CERTIFICATE_PARSER
select TSM
select AUXILIARY_BUS
+ select CRYPTO_ECDSA
+ select CRYPTO_RSA
help
ARM CCA RMM firmware is the trusted runtime that enforces memory
diff --git a/drivers/virt/coco/arm-cca-host/rmi-da.c b/drivers/virt/coco/arm-cca-host/rmi-da.c
index 644609618a7a..c9780ca64c17 100644
--- a/drivers/virt/coco/arm-cca-host/rmi-da.c
+++ b/drivers/virt/coco/arm-cca-host/rmi-da.c
@@ -8,6 +8,9 @@
#include <linux/pci-doe.h>
#include <linux/delay.h>
#include <asm/rmi_cmds.h>
+#include <crypto/internal/rsa.h>
+#include <keys/asymmetric-type.h>
+#include <keys/x509-parser.h>
#include "rmi-da.h"
@@ -361,6 +364,146 @@ static int do_pdev_communicate(struct pci_tsm *tsm, enum rmi_pdev_state target_s
return do_dev_communicate(PDEV_COMMUNICATE, tsm, target_state, RMI_PDEV_ERROR);
}
+static int parse_certificate_chain(struct pci_tsm *tsm)
+{
+ struct cca_host_pf0_dsc *pf0_dsc;
+ unsigned int chain_size;
+ unsigned int offset = 0;
+ u8 *chain_data;
+
+ pf0_dsc = to_cca_pf0_dsc(tsm->pdev);
+
+ /* If device communication didn't results in certificate caching. */
+ if (!pf0_dsc->cert_chain.cache || !pf0_dsc->cert_chain.cache->offset)
+ return -EINVAL;
+
+ chain_size = pf0_dsc->cert_chain.cache->offset;
+ chain_data = pf0_dsc->cert_chain.cache->buf;
+
+ while (offset < chain_size) {
+ ssize_t cert_len =
+ x509_get_certificate_length(chain_data + offset,
+ chain_size - offset);
+ if (cert_len < 0)
+ return cert_len;
+
+ struct x509_certificate *cert __free(x509_free_certificate) =
+ x509_cert_parse(chain_data + offset, cert_len);
+
+ if (IS_ERR(cert)) {
+ pci_warn(tsm->pdev, "parsing of certificate chain not successful\n");
+ return PTR_ERR(cert);
+ }
+
+ /* The key in the last cert in the chain is used */
+ if (offset + cert_len == chain_size) {
+ pf0_dsc->cert_chain.public_key = kzalloc(cert->pub->keylen, GFP_KERNEL);
+ if (!pf0_dsc->cert_chain.public_key)
+ return -ENOMEM;
+
+ if (!strcmp("ecdsa-nist-p256", cert->pub->pkey_algo)) {
+ pf0_dsc->rmi_signature_algorithm = RMI_SIG_ECDSA_P256;
+ } else if (!strcmp("ecdsa-nist-p384", cert->pub->pkey_algo)) {
+ pf0_dsc->rmi_signature_algorithm = RMI_SIG_ECDSA_P384;
+ } else if (!strcmp("rsa", cert->pub->pkey_algo)) {
+ pf0_dsc->rmi_signature_algorithm = RMI_SIG_RSASSA_3072;
+ } else {
+ kfree(pf0_dsc->cert_chain.public_key);
+ pf0_dsc->cert_chain.public_key = NULL;
+ return -ENXIO;
+ }
+ memcpy(pf0_dsc->cert_chain.public_key, cert->pub->key, cert->pub->keylen);
+ pf0_dsc->cert_chain.public_key_size = cert->pub->keylen;
+ }
+
+ offset += cert_len;
+ }
+
+ pf0_dsc->cert_chain.valid = true;
+ return 0;
+}
+
+DEFINE_FREE(free_page, unsigned long, if (_T) free_page(_T))
+static int pdev_set_public_key(struct pci_tsm *tsm)
+{
+ unsigned long expected_key_len;
+ struct cca_host_pf0_dsc *pf0_dsc;
+ int ret;
+
+ pf0_dsc = to_cca_pf0_dsc(tsm->pdev);
+ /* Check that all the necessary information was captured from communication */
+ if (!pf0_dsc->cert_chain.valid)
+ return -EINVAL;
+
+ struct rmi_public_key_params *key_params __free(free_page) =
+ (struct rmi_public_key_params *)get_zeroed_page(GFP_KERNEL);
+ if (!key_params)
+ return -ENOMEM;
+
+ key_params->rmi_signature_algorithm = pf0_dsc->rmi_signature_algorithm;
+
+ switch (key_params->rmi_signature_algorithm) {
+ case RMI_SIG_ECDSA_P384:
+ {
+ expected_key_len = 97;
+
+ if (pf0_dsc->cert_chain.public_key_size != expected_key_len)
+ return -EINVAL;
+
+ key_params->public_key_len = pf0_dsc->cert_chain.public_key_size;
+ memcpy(key_params->public_key,
+ pf0_dsc->cert_chain.public_key,
+ pf0_dsc->cert_chain.public_key_size);
+ key_params->metadata_len = 0;
+ break;
+ }
+ case RMI_SIG_ECDSA_P256:
+ {
+ expected_key_len = 65;
+
+ if (pf0_dsc->cert_chain.public_key_size != expected_key_len)
+ return -EINVAL;
+
+ key_params->public_key_len = pf0_dsc->cert_chain.public_key_size;
+ memcpy(key_params->public_key,
+ pf0_dsc->cert_chain.public_key,
+ pf0_dsc->cert_chain.public_key_size);
+ key_params->metadata_len = 0;
+ break;
+ }
+ case RMI_SIG_RSASSA_3072:
+ {
+ struct rsa_key rsa_key = {0};
+
+ expected_key_len = 385;
+ int ret_rsa_parse = rsa_parse_pub_key(&rsa_key,
+ pf0_dsc->cert_chain.public_key,
+ pf0_dsc->cert_chain.public_key_size);
+ /* This also checks the key_len */
+ if (ret_rsa_parse)
+ return ret_rsa_parse;
+ /*
+ * exponent is usually 65537 (size = 24bits) but in rare cases
+ * the size can be as large as the modulus
+ */
+ if (rsa_key.e_sz > expected_key_len)
+ return -EINVAL;
+
+ key_params->public_key_len = rsa_key.n_sz;
+ key_params->metadata_len = rsa_key.e_sz;
+ memcpy(key_params->public_key, rsa_key.n, rsa_key.n_sz);
+ memcpy(key_params->metadata, rsa_key.e, rsa_key.e_sz);
+ break;
+ }
+ default:
+ return -EINVAL;
+ }
+
+ ret = rmi_pdev_set_pubkey(virt_to_phys(pf0_dsc->rmm_pdev),
+ virt_to_phys(key_params));
+ return ret;
+}
+
void pdev_communicate_work(struct work_struct *work)
{
unsigned long state;
@@ -410,7 +553,28 @@ static int submit_pdev_comm_work(struct pci_dev *pdev, int target_state)
int pdev_ide_setup(struct pci_dev *pdev)
{
- return submit_pdev_comm_work(pdev, RMI_PDEV_NEEDS_KEY);
+ int ret;
+
+ ret = submit_pdev_comm_work(pdev, RMI_PDEV_NEEDS_KEY);
+ if (ret)
+ return ret;
+ /*
+ * we now have certificate chain in dsm->cert_chain. Parse
+ * that and set the pubkey.
+ */
+ ret = parse_certificate_chain(pdev->tsm);
+ if (ret)
+ return ret;
+
+ ret = pdev_set_public_key(pdev->tsm);
+ if (ret)
+ return ret;
+
+ ret = submit_pdev_comm_work(pdev, RMI_PDEV_READY);
+ if (ret)
+ return ret;
+
+ return 0;
}
void pdev_stop_and_destroy(struct pci_dev *pdev)
diff --git a/drivers/virt/coco/arm-cca-host/rmi-da.h b/drivers/virt/coco/arm-cca-host/rmi-da.h
index e556ccecc1cb..f1a840b6d4fb 100644
--- a/drivers/virt/coco/arm-cca-host/rmi-da.h
+++ b/drivers/virt/coco/arm-cca-host/rmi-da.h
@@ -51,6 +51,7 @@ struct cca_host_pf0_dsc {
int num_aux;
void *aux[MAX_PDEV_AUX_GRANULES];
+ uint8_t rmi_signature_algorithm;
struct mutex object_lock;
struct {
struct cache_object *cache;
--
2.43.0
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