On 2021-12-08 at 11:12:07 +0000, Matthew Auld wrote:
> On 08/12/2021 10:20, Ramalingam C wrote:
> > From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> >
> > As we setup the memory regions for the device, give each a quick test to
> > verify that we can read and write to the full iomem range. This ensures
> > that our physical addressing for the device's memory is correct, and
> > some reassurance that the memory is functional.
> >
> > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
> > Cc: CQ Tang <cq.tang@xxxxxxxxx>
> > Signed-off-by: Ramalingam C <ramalingam.c@xxxxxxxxx>
>
> For the series, assuming CI is happy now,
> Reviewed-by: Matthew Auld <matthew.auld@xxxxxxxxx>
Thank you!
>
> Also patch 3 should be moved to the start of the series.
Sure I will do it.
Ram.
>
> > ---
> > drivers/gpu/drm/i915/intel_memory_region.c | 104 +++++++++++++++++++++
> > 1 file changed, 104 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_memory_region.c b/drivers/gpu/drm/i915/intel_memory_region.c
> > index b43121609e25..c53e07f1d0c0 100644
> > --- a/drivers/gpu/drm/i915/intel_memory_region.c
> > +++ b/drivers/gpu/drm/i915/intel_memory_region.c
> > @@ -3,6 +3,8 @@
> > * Copyright © 2019 Intel Corporation
> > */
> > +#include <linux/prandom.h>
> > +
> > #include "intel_memory_region.h"
> > #include "i915_drv.h"
> > #include "i915_ttm_buddy_manager.h"
> > @@ -29,6 +31,99 @@ static const struct {
> > },
> > };
> > +static int __iopagetest(struct intel_memory_region *mem,
> > + u8 __iomem *va, int pagesize,
> > + u8 value, resource_size_t offset,
> > + const void *caller)
> > +{
> > + int byte = prandom_u32_max(pagesize);
> > + u8 result[3];
> > +
> > + memset_io(va, value, pagesize); /* or GPF! */
> > + wmb();
> > +
> > + result[0] = ioread8(va);
> > + result[1] = ioread8(va + byte);
> > + result[2] = ioread8(va + pagesize - 1);
> > + if (memchr_inv(result, value, sizeof(result))) {
> > + dev_err(mem->i915->drm.dev,
> > + "Failed to read back from memory region:%pR at [%pa + %pa] for %ps; wrote %x, read (%x, %x, %x)\n",
> > + &mem->region, &mem->io_start, &offset, caller,
> > + value, result[0], result[1], result[2]);
> > + return -EINVAL;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int iopagetest(struct intel_memory_region *mem,
> > + resource_size_t offset,
> > + const void *caller)
> > +{
> > + const u8 val[] = { 0x0, 0xa5, 0xc3, 0xf0 };
> > + void __iomem *va;
> > + int err;
> > + int i;
> > +
> > + va = ioremap_wc(mem->io_start + offset, PAGE_SIZE);
> > + if (!va) {
> > + dev_err(mem->i915->drm.dev,
> > + "Failed to ioremap memory region [%pa + %px] for %ps\n",
> > + &mem->io_start, &offset, caller);
> > + return -EFAULT;
> > + }
> > +
> > + for (i = 0; i < ARRAY_SIZE(val); i++) {
> > + err = __iopagetest(mem, va, PAGE_SIZE, val[i], offset, caller);
> > + if (err)
> > + break;
> > +
> > + err = __iopagetest(mem, va, PAGE_SIZE, ~val[i], offset, caller);
> > + if (err)
> > + break;
> > + }
> > +
> > + iounmap(va);
> > + return err;
> > +}
> > +
> > +static resource_size_t random_page(resource_size_t last)
> > +{
> > + /* Limited to low 44b (16TiB), but should suffice for a spot check */
> > + return prandom_u32_max(last >> PAGE_SHIFT) << PAGE_SHIFT;
> > +}
> > +
> > +static int iomemtest(struct intel_memory_region *mem, const void *caller)
> > +{
> > + resource_size_t last = resource_size(&mem->region) - PAGE_SIZE;
> > + int err;
> > +
> > + /*
> > + * Quick test to check read/write access to the iomap (backing store).
> > + *
> > + * Write a byte, read it back. If the iomapping fails, we expect
> > + * a GPF preventing further execution. If the backing store does not
> > + * exist, the read back will return garbage. We check a couple of pages,
> > + * the first and last of the specified region to confirm the backing
> > + * store + iomap does cover the entire memory region; and we check
> > + * a random offset within as a quick spot check for bad memory.
> > + */
> > +
> > + err = iopagetest(mem, 0, caller);
> > + if (err)
> > + return err;
> > +
> > + err = iopagetest(mem, last, caller);
> > + if (err)
> > + return err;
> > +
> > + err = iopagetest(mem, random_page(last), caller);
> > + if (err)
> > + return err;
> > +
> > + return 0;
> > +}
> > +
> > struct intel_memory_region *
> > intel_memory_region_lookup(struct drm_i915_private *i915,
> > u16 class, u16 instance)
> > @@ -126,8 +221,17 @@ intel_memory_region_create(struct drm_i915_private *i915,
> > goto err_free;
> > }
> > + if (io_start && IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)) {
> > + err = iomemtest(mem, (void *)_RET_IP_);
> > + if (err)
> > + goto err_release;
> > + }
> > +
> > return mem;
> > +err_release:
> > + if (mem->ops->release)
> > + mem->ops->release(mem);
> > err_free:
> > kfree(mem);
> > return ERR_PTR(err);
> >
