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  • 17 commits
  • 24 files changed
  • 6 contributors

Commits on Jul 21, 2023

  1. linux-user: Fix qemu brk() to not zero bytes on current page 

    The qemu brk() implementation is too aggressive and cleans remaining bytes
on the current page above the last brk address.

But some existing applications are buggy and read/write bytes above their
current heap address. On a phyiscal machine this does not trigger a
runtime error as long as the access happens on the same page. Additionally
the Linux kernel allocates only full pages and does no zeroing on already
allocated pages, even if the brk address is lowered.

Fix qemu to behave the same way as the kernel does. Do not touch already
allocated pages, and - when running with different page sizes of guest and
host - zero out only those memory areas where the host page size is bigger
than the guest page size.

Signed-off-by: Helge Deller <deller@gmx.de>
Tested-by: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>
Fixes: 86f0473 ("linux-user: Fix brk() to release pages")
Cc: qemu-stable@nongnu.org
Buglink: upx/upx#683
(cherry picked from commit 15ad985)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @hdeller
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  2. linux-user: Prohibit brk() to to shrink below initial heap address 

    Since commit 86f0473 ("linux-user: Fix brk() to release pages") it's
possible for userspace applications to reduce their memory footprint by
calling brk() with a lower address and free up memory. Before that commit
guest heap memory was never unmapped.

But the Linux kernel prohibits to reduce brk() below the initial memory
address which is set at startup by the set_brk() function in binfmt_elf.c.
Such a range check was missed in commit 86f0473.

This patch adds the missing check by storing the initial brk value in
initial_target_brk and verify any new brk addresses against that value.

Tested with the i386 upx binary from
https://github.com/upx/upx/releases/download/v4.0.2/upx-4.0.2-i386_linux.tar.xz

Signed-off-by: Helge Deller <deller@gmx.de>
Tested-by: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>
Fixes: 86f0473 ("linux-user: Fix brk() to release pages")
Cc: qemu-stable@nongnu.org
Buglink: upx/upx#683
(cherry picked from commit dfe4986)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @hdeller
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  3. linux-user: Fix signed math overflow in brk() syscall 

    Fix the math overflow when calculating the new_malloc_size.

new_host_brk_page and brk_page are unsigned integers. If userspace
reduces the heap, new_host_brk_page is lower than brk_page which results
in a huge positive number (but should actually be negative).

Fix it by adding a proper check and as such make the code more readable.

Signed-off-by: Helge Deller <deller@gmx.de>
Tested-by: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Fixes: 86f0473 ("linux-user: Fix brk() to release pages")
Cc: qemu-stable@nongnu.org
Buglink: upx/upx#683
(cherry picked from commit eac78a4)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @hdeller
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Commits on Jul 25, 2023

  1. qemu-nbd: pass structure into nbd_client_thread instead of plain char* 

    We are going to pass additional flag inside next patch.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
CC: <qemu-stable@nongnu.org>
Message-ID: <20230717145544.194786-2-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
(cherry picked from commit 03b6762)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    Denis V. Lunev authored and Michael Tokarev committed Jul 25, 2023
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  2. qemu-nbd: fix regression with qemu-nbd --fork run over ssh 

    Commit e6df58a
    Author: Hanna Reitz <hreitz@redhat.com>
    Date:   Wed May 8 23:18:18 2019 +0200
    qemu-nbd: Do not close stderr

has introduced an interesting regression. Original behavior of
    ssh somehost qemu-nbd /home/den/tmp/file -f raw --fork
was the following:
 * qemu-nbd was started as a daemon
 * the command execution is done and ssh exited with success

The patch has changed this behavior and 'ssh' command now hangs forever.

According to the normal specification of the daemon() call, we should
endup with STDERR pointing to /dev/null. That should be done at the
very end of the successful startup sequence when the pipe to the
bootstrap process (used for diagnostics) is no longer needed.

This could be achived in the same way as done for 'qemu-nbd -c' case.
That was commit 0eaf453, also fixing up e6df58a. STDOUT copying to
STDERR does the trick.

This also leads to proper 'ssh' connection closing which fixes my
original problem.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
CC: Hanna Reitz <hreitz@redhat.com>
CC: <qemu-stable@nongnu.org>
Message-ID: <20230717145544.194786-3-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
(cherry picked from commit 5c56dd2)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    Denis V. Lunev authored and Michael Tokarev committed Jul 25, 2023
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  3. tcg/ppc: Fix race in goto_tb implementation 

    Commit 20b6643 ("tcg/ppc: Reorg goto_tb implementation") modified
goto_tb to ensure only a single instruction was patched to prevent
incorrect behavior if a thread was in the middle of multiple
instructions when they were replaced. However this introduced a race
between loading the jmp target into TCG_REG_TB and patching and
executing the direct branch.

The relevant part of the goto_tb implementation:

    ld TCG_REG_TB, TARGET_ADDR_LOCATION(TCG_REG_TB)
  patch_location:
    mtctr TCG_REG_TB
    bctr

tb_target_set_jmp_target() will replace 'patch_location' with a direct
branch if the target is in range. The direct branch now relies on
TCG_REG_TB being set up correctly by the ld. Prior to this commit
multiple instructions were patched in for the direct branch case; these
instructions would initialize TCG_REG_TB to the same value as the branch
target.

Imagine the following sequence:

1) Thread A is executing the goto_tb sequence and loads the jmp
   target into TCG_REG_TB.

2) Thread B updates the jmp target address and calls
   tb_target_set_jmp_target(). This patches a new direct branch into the
   goto_tb sequence.

3) Thread A executes the newly patched direct branch. The value in
   TCG_REG_TB still contains the old jmp target.

TCG_REG_TB MUST contain the translation block's tc.ptr. Execution will
eventually crash after performing memory accesses generated from a
faulty value in TCG_REG_TB.

This presents as segfaults or illegal instruction exceptions.

Do not revert commit 20b6643 as it did fix a different race
condition. Instead remove the direct branch optimization and always use
indirect branches.

The direct branch optimization can be re-added later with a race free
sequence.

Fixes: 20b6643 ("tcg/ppc: Reorg goto_tb implementation")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1726
Reported-by: Anushree Mathur <anushree.mathur@linux.vnet.ibm.com>
Tested-by: Anushree Mathur <anushree.mathur@linux.vnet.ibm.com>
Tested-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Co-developed-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Message-Id: <20230717093001.13167-1-jniethe5@gmail.com>
(cherry picked from commit 736a158)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @iamjpn
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  4. tcg/{i386, s390x}: Add earlyclobber to the op_add2's first output 

    i386 and s390x implementations of op_add2 require an earlyclobber,
which is currently missing. This breaks VCKSM in s390x guests. E.g., on
x86_64 the following op:

    add2_i32 tmp2,tmp3,tmp2,tmp3,tmp3,tmp2   dead: 0 2 3 4 5  pref=none,0xffff

is translated to:

    addl     %ebx, %r12d
    adcl     %r12d, %ebx

Introduce a new C_N1_O1_I4 constraint, and make sure that earlyclobber
of aliased outputs is honored.

Cc: qemu-stable@nongnu.org
Fixes: 82790a8 ("tcg: Add markup for output requires new register")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230719221310.1968845-7-iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
(cherry picked from commit 22d2e53)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @iii-i
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  5. target/s390x: Make CKSM raise an exception if R2 is odd 

    R2 designates an even-odd register pair; the instruction should raise
a specification exception when R2 is not even.

Cc: qemu-stable@nongnu.org
Fixes: e023e83 ("s390x: translate engine for s390x CPU")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230724082032.66864-2-iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 761b0aa)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @iii-i
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  6. target/s390x: Fix CLM with M3=0 

    When the mask is zero, access exceptions should still be recognized for
1 byte at the second-operand address. CC should be set to 0.

Cc: qemu-stable@nongnu.org
Fixes: defb0e3 ("s390x: Implement opcode helpers")
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230724082032.66864-3-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 4b6e4c0)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @iii-i
    iii-i authored and Michael Tokarev committed Jul 25, 2023
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  7. target/s390x: Fix CONVERT TO LOGICAL/FIXED with out-of-range inputs 

    CONVERT TO LOGICAL/FIXED deviate from IEEE 754 in that they raise an
inexact exception on out-of-range inputs. float_flag_invalid_cvti
aligns nicely with that behavior, so convert it to
S390_IEEE_MASK_INEXACT.

Cc: qemu-stable@nongnu.org
Fixes: defb0e3 ("s390x: Implement opcode helpers")
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230724082032.66864-4-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 53684e3)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @iii-i
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  8. target/s390x: Fix ICM with M3=0 

    When the mask is zero, access exceptions should still be recognized for
1 byte at the second-operand address. CC should be set to 0.

Cc: qemu-stable@nongnu.org
Fixes: e023e83 ("s390x: translate engine for s390x CPU")
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230724082032.66864-5-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit a202555)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @iii-i
    iii-i authored and Michael Tokarev committed Jul 25, 2023
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  9. target/s390x: Make MC raise specification exception when class >= 16 

    MC requires bit positions 8-11 (upper 4 bits of class) to be zeros,
otherwise it must raise a specification exception.

Cc: qemu-stable@nongnu.org
Fixes: 20d143e ("s390x/tcg: Implement MONITOR CALL")
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230724082032.66864-6-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 9c028c0)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @iii-i
    iii-i authored and Michael Tokarev committed Jul 25, 2023
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  10. target/s390x: Fix assertion failure in VFMIN/VFMAX with type 13 

    Type 13 is reserved, so using it should result in specification
exception. Due to an off-by-1 error the code triggers an assertion at a
later point in time instead.

Cc: qemu-stable@nongnu.org
Fixes: da48075 ("s390x/tcg: Implement VECTOR FP (MAXIMUM|MINIMUM)")
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230724082032.66864-8-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit ff537b0)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @iii-i
    iii-i authored and Michael Tokarev committed Jul 25, 2023
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  11. target/loongarch: Fix the CSRRD CPUID instruction on big endian hosts 

    The test in tests/avocado/machine_loongarch.py is currently failing
on big endian hosts like s390x. By comparing the traces between running
the QEMU_EFI.fd bios on a s390x and on a x86 host, it's quickly obvious
that the CSRRD instruction for the CPUID is behaving differently. And
indeed: The code currently does a long read (i.e. 64 bit) from the
address that points to the CPUState->cpu_index field (with tcg_gen_ld_tl()
in the trans_csrrd() function). But this cpu_index field is only an "int"
(i.e. 32 bit). While this dirty pointer magic works on little endian hosts,
it of course fails on big endian hosts. Fix it by using a proper helper
function instead.

Message-Id: <20230720175307.854460-1-thuth@redhat.com>
Reviewed-by: Song Gao <gaosong@loongson.cn>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit c34ad45)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @huth
    huth authored and Michael Tokarev committed Jul 25, 2023
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  12. virtio-pci: add handling of PCI ATS and Device-TLB enable/disable 

    According to PCIe Address Translation Services specification 5.1.3.,
ATS Control Register has Enable bit to enable/disable ATS. Guest may
enable/disable PCI ATS and, accordingly, Device-TLB for the VirtIO PCI
device. So, raise/lower a flag and call a trigger function to pass this
event to a device implementation.

Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
Message-Id: <20230512135122.70403-2-viktor@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 206e91d)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @viktor-prutyanov
    viktor-prutyanov authored and Michael Tokarev committed Jul 25, 2023
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  13. vhost: register and change IOMMU flag depending on Device-TLB state 

    The guest can disable or never enable Device-TLB. In these cases,
it can't be used even if enabled in QEMU. So, check Device-TLB state
before registering IOMMU notifier and select unmap flag depending on
that. Also, implement a way to change IOMMU notifier flag if Device-TLB
state is changed.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2001312
Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230626091258.24453-2-viktor@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit ee071f6)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @viktor-prutyanov
    viktor-prutyanov authored and Michael Tokarev committed Jul 25, 2023
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  14. virtio-net: pass Device-TLB enable/disable events to vhost 

    If vhost is enabled for virtio-net, Device-TLB enable/disable events
must be passed to vhost for proper IOMMU unmap flag selection.

Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230626091258.24453-3-viktor@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit cd9b834)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
    @viktor-prutyanov
    viktor-prutyanov authored and Michael Tokarev committed Jul 25, 2023
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