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80 lines
2.7 KiB
80 lines
2.7 KiB
From 7f3f6e3088655e33600aacd886aa51d19c01c59a Mon Sep 17 00:00:00 2001
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From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Wed, 19 Jul 2023 18:31:29 +0200
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Subject: [PATCH 2/3] OvmfPkg/IoMmuDxe: add locking to
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IoMmuAllocateBounceBuffer
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RH-Author: Gerd Hoffmann <None>
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RH-MergeRequest: 45: OvmfPkg/IoMmuDxe: add locking to IoMmuAllocateBounceBuffer
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RH-Bugzilla: 2211060
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RH-Acked-by: Oliver Steffen <osteffen@redhat.com>
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RH-Commit: [1/1] c4998c57651df23342a0cd6e8982bf59f306da83 (kraxel.rh/centos-src-edk2)
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Searching for an unused bounce buffer in mReservedMemBitmap and
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reserving the buffer by flipping the bit is a critical section
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which must not be interrupted. Raise the TPL level to ensure
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that.
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Without this fix it can happen that IoMmuDxe hands out the same
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bounce buffer twice, causing trouble down the road. Seen happening
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in practice with VirtioNetDxe setting up the network interface (and
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calling into IoMmuDxe from a polling timer callback) in parallel with
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Boot Manager doing some disk I/O. An ASSERT() in VirtioNet caught
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the buffer inconsistency.
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Full story with lots of details and discussions is available here:
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https://bugzilla.redhat.com/show_bug.cgi?id=2211060
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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(cherry picked from commit a52044a9e602bc168cdf5d73a48952bfc9edb521)
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---
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OvmfPkg/IoMmuDxe/IoMmuBuffer.c | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/OvmfPkg/IoMmuDxe/IoMmuBuffer.c b/OvmfPkg/IoMmuDxe/IoMmuBuffer.c
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index c8f6cf4818..103003cae3 100644
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--- a/OvmfPkg/IoMmuDxe/IoMmuBuffer.c
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+++ b/OvmfPkg/IoMmuDxe/IoMmuBuffer.c
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@@ -367,7 +367,9 @@ IoMmuAllocateBounceBuffer (
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{
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EFI_STATUS Status;
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UINT32 ReservedMemBitmap;
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+ EFI_TPL OldTpl;
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+ OldTpl = gBS->RaiseTPL (TPL_NOTIFY);
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ReservedMemBitmap = 0;
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Status = InternalAllocateBuffer (
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Type,
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@@ -378,6 +380,7 @@ IoMmuAllocateBounceBuffer (
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);
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MapInfo->ReservedMemBitmap = ReservedMemBitmap;
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mReservedMemBitmap |= ReservedMemBitmap;
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+ gBS->RestoreTPL (OldTpl);
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ASSERT (Status == EFI_SUCCESS);
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@@ -395,6 +398,8 @@ IoMmuFreeBounceBuffer (
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IN OUT MAP_INFO *MapInfo
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)
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{
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+ EFI_TPL OldTpl;
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+
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if (MapInfo->ReservedMemBitmap == 0) {
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gBS->FreePages (MapInfo->PlainTextAddress, MapInfo->NumberOfPages);
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} else {
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@@ -407,9 +412,11 @@ IoMmuFreeBounceBuffer (
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mReservedMemBitmap,
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mReservedMemBitmap & ((UINT32)(~MapInfo->ReservedMemBitmap))
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));
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+ OldTpl = gBS->RaiseTPL (TPL_NOTIFY);
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MapInfo->PlainTextAddress = 0;
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mReservedMemBitmap &= (UINT32)(~MapInfo->ReservedMemBitmap);
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MapInfo->ReservedMemBitmap = 0;
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+ gBS->RestoreTPL (OldTpl);
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}
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return EFI_SUCCESS;
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--
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2.39.3
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