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Re: [Qemu-devel] [PATCH v10 3/6] tpm: allocate/map buffer for TPM Physic
Re: [Qemu-devel] [PATCH v10 3/6] tpm: allocate/map buffer for TPM Physical Presence interface
Tue, 4 Sep 2018 08:51:52 +0200
On Mon, 03 Sep 2018 23:48:15 +0200
Juan Quintela <address@hidden> wrote:
> Marc-André Lureau <address@hidden> wrote:
> > Hi
> > On Fri, Aug 31, 2018 at 7:32 PM Marc-André Lureau
> > <address@hidden> wrote:
> >> From: Stefan Berger <address@hidden>
> >> Implement a virtual memory device for the TPM Physical Presence interface.
> >> The memory is located at 0xFED45000 and used by ACPI to send messages to
> >> the
> >> firmware (BIOS) and by the firmware to provide parameters for each one of
> >> the supported codes.
> >> This interface should be used by all TPM devices on x86 and can be
> >> added by calling tpm_ppi_init_io().
> >> Note: bios_linker cannot be used to allocate the PPI memory region,
> >> since the reserved memory should stay stable across reboots, and might
> >> be needed before the ACPI tables are installed.
> >> Signed-off-by: Stefan Berger <address@hidden>
> >> Signed-off-by: Marc-André Lureau <address@hidden>
> >> Reviewed-by: Igor Mammedov <address@hidden>
> >> + */
> >> +#define TPM_PPI_ADDR_SIZE 0x400
> >> +#define TPM_PPI_ADDR_BASE 0xFED45000
> > There is a (new) issue with the PPI ram region:
> > READ of size 32 at 0x61d000090480 thread T6
> > #0 0x5622bd8de0f4 in buffer_zero_avx2
> > /home/elmarco/src/qq/util/bufferiszero.c:169
> > #1 0x5622bd8de899 in select_accel_fn
> > /home/elmarco/src/qq/util/bufferiszero.c:282
> > #2 0x5622bd8de8f1 in buffer_is_zero
> > /home/elmarco/src/qq/util/bufferiszero.c:309
> > #3 0x5622bc209f94 in is_zero_range
> > /home/elmarco/src/qq/migration/ram.c:82
> > #4 0x5622bc21938d in save_zero_page_to_file
> > /home/elmarco/src/qq/migration/ram.c:1694
> > #5 0x5622bc219452 in save_zero_page
> > /home/elmarco/src/qq/migration/ram.c:1713
> > #6 0x5622bc21db67 in ram_save_target_page
> > /home/elmarco/src/qq/migration/ram.c:2289
> > #7 0x5622bc21e13e in ram_save_host_page
> > /home/elmarco/src/qq/migration/ram.c:2351
> > #8 0x5622bc21ea3a in ram_find_and_save_block
> > /home/elmarco/src/qq/migration/ram.c:2413
> > #9 0x5622bc223b5d in ram_save_iterate
> > /home/elmarco/src/qq/migration/ram.c:3193
> > #10 0x5622bd16f544 in qemu_savevm_state_iterate
> > /home/elmarco/src/qq/migration/savevm.c:1103
> > #11 0x5622bd157e75 in migration_iteration_run
> > /home/elmarco/src/qq/migration/migration.c:2897
> > #12 0x5622bd15892e in migration_thread
> > /home/elmarco/src/qq/migration/migration.c:3018
> > #13 0x5622bd902f31 in qemu_thread_start
> > /home/elmarco/src/qq/util/qemu-thread-posix.c:504
> > #14 0x7f42f0ef4593 in start_thread (/lib64/libpthread.so.0+0x7593)
> > #15 0x7f42f0c280de in clone (/lib64/libc.so.6+0xfa0de)
> > 0x61d000090490 is located 0 bytes to the right of 2064-byte region
> > [0x61d00008fc80,0x61d000090490)
> > migration code is assuming RAM is multiple of TARGET_PAGE_SIZE.
> Physical RAM is multiple of TARGET_PAGE_SIZE O:-)
> That assumtion is held in too many places, if you can change the size to
> be multiple of page size, that would be greate.
> > Should the migration code be fixed, or should the TPM code allocate
> > ram differently?
> Migration people (i.e. me) would preffer that you fix the TPM
> allocation. Or you can decide that this is *not* RAM. The unit of
> transfer for migrate ram is ram pages, a.k.a. TARGET_PAGE_SIZE.
I'd loath to waste whole page in already cramped area.
Can we implement it as mmio region? (it will add some bolerplate code for
handlers/migration and cause vmexits on every read/write but it's not a hot
path so we might not care)
> > In all case, I think the migration code should either be fixed or have
> > an assert.
> An assert for sure.
> Fixed .... Do we have real devices that put ram regions that are smaller
> than page size?
> Later, Juan.