[ena] Provide a host information page

Some versions of the ENA firmware (observed on a c6i.large instance in
eu-west-2) seem to require a host information page, without which the
CREATE_CQ command will fail with ENA_ADMIN_UNKNOWN_ERROR.

These firmware versions also seem to require us to claim that we are a
Linux kernel with a specific driver major version number.  This
appears to be a firmware bug, as revealed by Linux kernel commit
1a63443af ("net/amazon: Ensure that driver version is aligned to the
linux kernel"): this commit changed the value of the driver version
number field to be the Linux kernel version, and was hastily reverted
in commit 92040c6da ("net: ena: fix broken interface between ENA
driver and FW") which clarified that the version number field does
actually have some undocumented significance to some versions of the
firmware.

Fix by providing a host information page via the SET_FEATURE command,
incorporating the apparently necessary lies about our identity.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 101 insertions, 0 deletions

diff --git a/src/drivers/net/ena.h b/src/drivers/net/ena.h
index 78693e678..cbee1e768 100644
--- a/src/drivers/net/ena.h
+++ b/src/drivers/net/ena.h
@@ -127,10 +127,86 @@ struct ena_device_attributes {
 	uint32_t mtu;
 } __attribute__ (( packed ));
 
+/** Host attributes */
+#define ENA_HOST_ATTRIBUTES 28
+
+/** Host attributes */
+struct ena_host_attributes {
+	/** Host info base address */
+	uint64_t info;
+	/** Debug area base address */
+	uint64_t debug;
+	/** Debug area size */
+	uint32_t debug_len;
+} __attribute__ (( packed ));
+
+/** Host information */
+struct ena_host_info {
+	/** Operating system type */
+	uint32_t type;
+	/** Operating system distribution (string) */
+	char dist_str[128];
+	/** Operating system distribution (numeric) */
+	uint32_t dist;
+	/** Kernel version (string) */
+	char kernel_str[32];
+	/** Kernel version (numeric) */
+	uint32_t kernel;
+	/** Driver version */
+	uint32_t version;
+	/** Linux network device features */
+	uint64_t linux_features;
+	/** ENA specification version */
+	uint16_t spec;
+	/** PCI bus:dev.fn address */
+	uint16_t busdevfn;
+	/** Number of CPUs */
+	uint16_t cpus;
+	/** Reserved */
+	uint8_t reserved_a[2];
+	/** Supported features */
+	uint32_t features;
+} __attribute__ (( packed ));
+
+/** Linux operating system type
+ *
+ * There is a defined "iPXE" operating system type (with value 5).
+ * However, some very broken versions of the ENA firmware will refuse
+ * to allow a completion queue to be created if the "iPXE" type is
+ * used.
+ */
+#define ENA_HOST_INFO_TYPE_LINUX 1
+
+/** Driver version
+ *
+ * The driver version field is nominally used to report a version
+ * number outside of the VM for consumption by humans (and potentially
+ * by automated monitoring tools that could e.g. check for outdated
+ * versions with known security flaws).
+ *
+ * However, at some point in the development of the ENA firmware, some
+ * unknown person at AWS thought it would be sensible to apply a
+ * machine interpretation to this field and adjust the behaviour of
+ * the firmware based on its value, thereby creating a maintenance and
+ * debugging nightmare for all existing and future drivers.
+ *
+ * Hint to engineers: if you ever find yourself writing code of the
+ * form "if (version == SOME_MAGIC_NUMBER)" then something has gone
+ * very, very wrong.  This *always* indicates that something is
+ * broken, either in your own code or in the code with which you are
+ * forced to interact.
+ */
+#define ENA_HOST_INFO_VERSION_WTF 0x00000002UL
+
+/** ENA specification version */
+#define ENA_HOST_INFO_SPEC_2_0 0x0200
+
 /** Feature */
 union ena_feature {
 	/** Device attributes */
 	struct ena_device_attributes device;
+	/** Host attributes */
+	struct ena_host_attributes host;
 };
 
 /** Submission queue direction */
@@ -300,6 +376,27 @@ struct ena_get_feature_rsp {
 	union ena_feature feature;
 } __attribute__ (( packed ));
 
+/** Set feature */
+#define ENA_SET_FEATURE 9
+
+/** Set feature request */
+struct ena_set_feature_req {
+	/** Header */
+	struct ena_aq_header header;
+	/** Length */
+	uint32_t len;
+	/** Address */
+	uint64_t address;
+	/** Flags */
+	uint8_t flags;
+	/** Feature identifier */
+	uint8_t id;
+	/** Reserved */
+	uint8_t reserved[2];
+	/** Feature */
+	union ena_feature feature;
+} __attribute__ (( packed ));
+
 /** Get statistics */
 #define ENA_GET_STATS 11
 
@@ -360,6 +457,8 @@ union ena_aq_req {
 	struct ena_destroy_cq_req destroy_cq;
 	/** Get feature */
 	struct ena_get_feature_req get_feature;
+	/** Set feature */
+	struct ena_set_feature_req set_feature;
 	/** Get statistics */
 	struct ena_get_stats_req get_stats;
 	/** Padding */
@@ -590,6 +689,8 @@ struct ena_qp {
 struct ena_nic {
 	/** Registers */
 	void *regs;
+	/** Host info */
+	struct ena_host_info *info;
 	/** Admin queue */
 	struct ena_aq aq;
 	/** Admin completion queue */