update NestedInterruptTplLib patches
This commit is contained in:
Gerd Hoffmann
parent
82b6b6aa9f
commit
9839d74e46
@ -0,0 +1,66 @@
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From 51846ff74e3352151f99cfcfbe091c09f3ec8097 Mon Sep 17 00:00:00 2001
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From: Michael Brown <mcb30@ipxe.org>
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Date: Tue, 9 May 2023 12:09:30 +0000
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Subject: [PATCH 16/18] OvmfPkg: Clarify invariants for NestedInterruptTplLib
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NestedInterruptTplLib relies on CPU interrupts being disabled to
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guarantee exclusive (and hence atomic) access to the shared state in
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IsrState. Nothing in the calling interrupt handler should have
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re-enabled interrupts before calling NestedInterruptRestoreTPL(), and
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the loop in NestedInterruptRestoreTPL() itself maintains the invariant
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that interrupts are disabled at the start of each iteration.
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Add assertions to clarify this invariant, and expand the comments
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around the calls to RestoreTPL() and DisableInterrupts() to clarify
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the expectations around enabling and disabling interrupts.
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Signed-off-by: Michael Brown <mcb30@ipxe.org>
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Acked-by: Laszlo Ersek <lersek@redhat.com>
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(cherry picked from commit ae0be176a83efebe9a8c13d2124151f7dd13443a)
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---
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OvmfPkg/Library/NestedInterruptTplLib/Tpl.c | 10 ++++++++--
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1 file changed, 8 insertions(+), 2 deletions(-)
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diff --git a/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c b/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c
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index e19d98878eb7..e921a09c5599 100644
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--- a/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c
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+++ b/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c
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@@ -104,6 +104,7 @@ NestedInterruptRestoreTPL (
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// defer our call to RestoreTPL() to the in-progress outer instance
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// of the same interrupt handler.
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//
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+ ASSERT (GetInterruptState () == FALSE);
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if (InterruptedTPL == IsrState->InProgressRestoreTPL) {
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//
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// Trigger outer instance of this interrupt handler to perform the
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@@ -153,6 +154,7 @@ NestedInterruptRestoreTPL (
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//
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// Check shared state loop invariants.
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//
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+ ASSERT (GetInterruptState () == FALSE);
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ASSERT (IsrState->InProgressRestoreTPL < InterruptedTPL);
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ASSERT (IsrState->DeferredRestoreTPL == FALSE);
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@@ -167,13 +169,17 @@ NestedInterruptRestoreTPL (
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//
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// Call RestoreTPL() to allow event notifications to be
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- // dispatched. This will implicitly re-enable interrupts.
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+ // dispatched. This will implicitly re-enable interrupts (if
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+ // InterruptedTPL is below TPL_HIGH_LEVEL), even though we are
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+ // still inside the interrupt handler.
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//
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gBS->RestoreTPL (InterruptedTPL);
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//
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// Re-disable interrupts after the call to RestoreTPL() to ensure
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- // that we have exclusive access to the shared state.
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+ // that we have exclusive access to the shared state. Interrupts
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+ // will be re-enabled by the IRET or equivalent instruction when
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+ // we subsequently return from the interrupt handler.
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//
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DisableInterrupts ();
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--
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2.40.1
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@ -1,40 +0,0 @@
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From 7c65395d2b45e388c6c106cb619ab93c2359f5e4 Mon Sep 17 00:00:00 2001
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From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Thu, 27 Apr 2023 12:14:16 +0200
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Subject: [PATCH 16/17] OvmfPkg/NestedInterruptTplLib: replace ASSERT() with a
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warning logged.
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OVMF can't guarantee that the ASSERT() doesn't happen. Misbehaving
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EFI applications can trigger this. So log a warning instead and try
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to continue.
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Reproducer: Fetch windows 11 22H2 iso image, boot it in qemu with OVMF.
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Traced to BootServices->Stall() being called with IPL=TPL_HIGH_LEVEL
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and Interrupts /enabled/ while windows is booting.
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Cc: Michael Brown <mcb30@ipxe.org>
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Cc: Laszlo Ersek <lersek@redhat.com>
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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---
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OvmfPkg/Library/NestedInterruptTplLib/Tpl.c | 4 +++-
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1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c b/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c
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index e19d98878eb7..fdd7d15c4ba8 100644
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--- a/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c
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+++ b/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c
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@@ -39,7 +39,9 @@ NestedInterruptRaiseTPL (
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//
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ASSERT (GetInterruptState () == FALSE);
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InterruptedTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
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- ASSERT (InterruptedTPL < TPL_HIGH_LEVEL);
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+ if (InterruptedTPL >= TPL_HIGH_LEVEL) {
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+ DEBUG ((DEBUG_WARN, "%a: Called at IPL %d\n", __func__, InterruptedTPL));
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+ }
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return InterruptedTPL;
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}
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--
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2.40.1
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@ -0,0 +1,75 @@
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From 7272c2fbe66941f0785be7ec437ed79ab9e35b80 Mon Sep 17 00:00:00 2001
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From: Michael Brown <mcb30@ipxe.org>
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Date: Tue, 9 May 2023 12:09:33 +0000
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Subject: [PATCH 17/18] OvmfPkg: Relax assertion that interrupts do not occur
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at TPL_HIGH_LEVEL
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At TPL_HIGH_LEVEL, CPU interrupts are disabled (as per the UEFI
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specification) and so we should never encounter a situation in which
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an interrupt occurs at TPL_HIGH_LEVEL. The specification also
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restricts usage of TPL_HIGH_LEVEL to the firmware itself.
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However, nothing actually prevents a UEFI application from calling
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gBS->RaiseTPL(TPL_HIGH_LEVEL) and then violating the invariant by
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enabling interrupts via the STI or equivalent instruction. Some
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versions of the Microsoft Windows bootloader are known to do this.
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NestedInterruptTplLib maintains the invariant that interrupts are
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disabled at TPL_HIGH_LEVEL (even when performing the dark art of
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deliberately manipulating the stack so that IRET will return with
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interrupts still disabled), but does not itself rely on external code
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maintaining this invariant.
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Relax the assertion that the interrupted TPL is below TPL_HIGH_LEVEL
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to an error message, to allow UEFI applications such as these versions
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of the Microsoft Windows bootloader to continue to function.
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Debugged-by: Gerd Hoffmann <kraxel@redhat.com>
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Debugged-by: Laszlo Ersek <lersek@redhat.com>
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Ref: https://bugzilla.redhat.com/show_bug.cgi?id=2189136
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Signed-off-by: Michael Brown <mcb30@ipxe.org>
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Acked-by: Laszlo Ersek <lersek@redhat.com>
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Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
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(cherry picked from commit bee67e0c142af6599a85aa7640094816b8a24c4f)
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---
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OvmfPkg/Library/NestedInterruptTplLib/Tpl.c | 21 ++++++++++++++++++---
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1 file changed, 18 insertions(+), 3 deletions(-)
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diff --git a/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c b/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c
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index e921a09c5599..d56c12a44529 100644
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--- a/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c
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+++ b/OvmfPkg/Library/NestedInterruptTplLib/Tpl.c
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@@ -34,12 +34,27 @@ NestedInterruptRaiseTPL (
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//
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// Raise TPL and assert that we were called from within an interrupt
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- // handler (i.e. with TPL below TPL_HIGH_LEVEL but with interrupts
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- // disabled).
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+ // handler (i.e. with interrupts already disabled before raising the
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+ // TPL).
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//
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ASSERT (GetInterruptState () == FALSE);
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InterruptedTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
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- ASSERT (InterruptedTPL < TPL_HIGH_LEVEL);
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+
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+ //
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+ // At TPL_HIGH_LEVEL, CPU interrupts are disabled (as per the UEFI
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+ // specification) and so we should never encounter a situation in
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+ // which InterruptedTPL==TPL_HIGH_LEVEL. The specification also
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+ // restricts usage of TPL_HIGH_LEVEL to the firmware itself.
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+ //
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+ // However, nothing actually prevents a UEFI application from
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+ // invalidly calling gBS->RaiseTPL(TPL_HIGH_LEVEL) and then
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+ // violating the invariant by enabling interrupts via the STI or
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+ // equivalent instruction. Some versions of the Microsoft Windows
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+ // bootloader are known to do this.
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+ //
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+ if (InterruptedTPL >= TPL_HIGH_LEVEL) {
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+ DEBUG ((DEBUG_ERROR, "ERROR: Interrupts enabled at TPL_HIGH_LEVEL!\n"));
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+ }
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return InterruptedTPL;
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}
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--
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2.40.1
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@ -98,7 +98,8 @@ Patch0012: 0012-OvmfPkg-QemuKernelLoaderFsDxe-suppress-error-on-no-k.patch
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Patch0013: 0013-SecurityPkg-Tcg2Dxe-suppress-error-on-no-swtpm-in-si.patch
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Patch0014: 0014-SecurityPkg-add-TIS-sanity-check-tpm2.patch
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Patch0015: 0015-SecurityPkg-add-TIS-sanity-check-tpm12.patch
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Patch0016: 0016-OvmfPkg-NestedInterruptTplLib-replace-ASSERT-with-a-.patch
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Patch0016: 0016-OvmfPkg-Clarify-invariants-for-NestedInterruptTplLib.patch
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Patch0017: 0017-OvmfPkg-Relax-assertion-that-interrupts-do-not-occur.patch
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# python3-devel and libuuid-devel are required for building tools.
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