cxl: Support the cxl kernel API from a guest

Like on bare-metal, the cxl driver creates a virtual PHB and a pci
device for the AFU. The configuration space of the device is mapped to
the configuration record of the AFU.

Reuse the code defined in afu_cr_read8|16|32() when reading the
configuration space of the AFU device.

Even though the (virtual) AFU device is a pci device, the adapter is
not. So a driver using the cxl kernel API cannot read the VPD of the
adapter through the usual PCI interface. Therefore, we add a call to
the cxl kernel API:
ssize_t cxl_read_adapter_vpd(struct pci_dev *dev, void *buf, size_t count);

Co-authored-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: Manoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 50 insertions, 0 deletions

diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
index 0e289c22cdec..e564ae657584 100644
--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -1019,6 +1019,52 @@ static int native_afu_cr_read8(struct cxl_afu *afu, int cr, u64 off, u8 *out)
         return rc;
 }
 
+static int native_afu_cr_write32(struct cxl_afu *afu, int cr, u64 off, u32 in)
+{
+        if (unlikely(!cxl_ops->link_ok(afu->adapter)))
+                return -EIO;
+        if (unlikely(off >= afu->crs_len))
+                return -ERANGE;
+        out_le32(afu->native->afu_desc_mmio + afu->crs_offset +
+                (cr * afu->crs_len) + off, in);
+        return 0;
+}
+
+static int native_afu_cr_write16(struct cxl_afu *afu, int cr, u64 off, u16 in)
+{
+        u64 aligned_off = off & ~0x3L;
+        u32 val32, mask, shift;
+        int rc;
+
+        rc = native_afu_cr_read32(afu, cr, aligned_off, &val32);
+        if (rc)
+                return rc;
+        shift = (off & 0x3) * 8;
+        WARN_ON(shift == 24);
+        mask = 0xffff << shift;
+        val32 = (val32 & ~mask) | (in << shift);
+
+        rc = native_afu_cr_write32(afu, cr, aligned_off, val32);
+        return rc;
+}
+
+static int native_afu_cr_write8(struct cxl_afu *afu, int cr, u64 off, u8 in)
+{
+        u64 aligned_off = off & ~0x3L;
+        u32 val32, mask, shift;
+        int rc;
+
+        rc = native_afu_cr_read32(afu, cr, aligned_off, &val32);
+        if (rc)
+                return rc;
+        shift = (off & 0x3) * 8;
+        mask = 0xff << shift;
+        val32 = (val32 & ~mask) | (in << shift);
+
+        rc = native_afu_cr_write32(afu, cr, aligned_off, val32);
+        return rc;
+}
+
 const struct cxl_backend_ops cxl_native_ops = {
         .module = THIS_MODULE,
         .adapter_reset = cxl_pci_reset,
@@ -1044,4 +1090,8 @@ const struct cxl_backend_ops cxl_native_ops = {
         .afu_cr_read16 = native_afu_cr_read16,
         .afu_cr_read32 = native_afu_cr_read32,
         .afu_cr_read64 = native_afu_cr_read64,
+        .afu_cr_write8 = native_afu_cr_write8,
+        .afu_cr_write16 = native_afu_cr_write16,
+        .afu_cr_write32 = native_afu_cr_write32,
+        .read_adapter_vpd = cxl_pci_read_adapter_vpd,
 };