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dev-amdgpu: Place all user-mode translations in MMHUB

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The memory management hub ("mmhub") is an aperture that aliases the GPU
device memory. MMHUB addresses functionally map to the same device
address, with the exception that it is guaranteed not to overlap with
host memory. This is useful in gem5 for APIs with Addr type as it
prevents sending e.g., DMAs to the wrong place.

Change-Id: Ia296809a8dc2c5fbdeba6d70cd53215f9ab36c93
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/63031
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This commit is contained in:
Matthew Poremba
2022-08-27 16:50:44 -07:00
parent e0e2806fc4
commit 9ed39afe62
1 changed files with 11 additions and 3 deletions
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14
src/dev/amdgpu/amdgpu_vm.cc
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@@ -331,11 +331,11 @@ AMDGPUVM::UserTranslationGen::translate(Range &range) const
DPRINTF(AMDGPUDevice, "User tl base %#lx start %#lx walker %p\n",
base, start, walker);
bool dummy;
bool system_bit;
unsigned logBytes;
Addr paddr = range.vaddr;
Fault fault = walker->startFunctional(base, paddr, logBytes,
BaseMMU::Mode::Read, dummy);
BaseMMU::Mode::Read, system_bit);
if (fault != NoFault) {
fatal("User translation fault");
}
@@ -343,9 +343,17 @@ AMDGPUVM::UserTranslationGen::translate(Range &range) const
// GPU page size is variable. Use logBytes to determine size.
const Addr page_size = 1 << logBytes;
Addr next = roundUp(range.vaddr, page_size);
if (next == range.vaddr)
if (next == range.vaddr) {
// We don't know the size of the next page, use default.
next += AMDGPU_USER_PAGE_SIZE;
}
// If we are not in system/host memory, change the address to the MMHUB
// aperture. This is mapped to the same backing memory as device memory.
if (!system_bit) {
paddr += vm->getMMHUBBase();
assert(vm->inMMHUB(paddr));
}
range.size = std::min(range.size, next - range.vaddr);
range.paddr = paddr;