haraldwolff/qemu-patch-raspberry4
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pseries: Allow writes to KVM accelerated TCE table

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Sufficiently recent kernels include a KVM call to accelerate use of
PAPR TCE tables (IOMMU), which are used by PAPR virtual IO devices.
This involves qemu mapping the TCE table in from a kernel obtained fd,
which currently we do with PROT_READ only.  This is a hangover from
early (never released) versions of this kernel interface which only
permitted read-only mappings and required us to destroy and recreate
the table when we needed to clear it from qemu.

Now, the kernel permits read-write mappings, and we rely on this to
clear the table in spapr_vio_quiesce_one().  However, due to
insufficient testing, I forgot to update the actual mapping of the
table in kvmppc_create_spapr_tce() to add PROT_WRITE to the mmap().

This patch corrects the oversight.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
David Gibson 2011-10-27 15:56:31 +00:00 committed by Alexander Graf
parent 70bca53ffb
commit 74b41e5676
1 changed files with 1 additions and 1 deletions
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2
target-ppc/kvm.c
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@ -850,7 +850,7 @@ void *kvmppc_create_spapr_tce(uint32_t liobn, uint32_t window_size, int *pfd)
len = (window_size / SPAPR_VIO_TCE_PAGE_SIZE) * sizeof(VIOsPAPR_RTCE);
/* FIXME: round this up to page size */
table = mmap(NULL, len, PROT_READ, MAP_SHARED, fd, 0);
table = mmap(NULL, len, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (table == MAP_FAILED) {
close(fd);
return NULL;