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authorHaren Myneni <haren@linux.vnet.ibm.com>2012-12-06 21:51:04 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-01-10 17:01:13 +1100
commit44e9309f1f357794b7ae93d5f3e3e6f11d2b8a7f (patch)
tree3bfa0ffc5014355234fd8b7d45e49b0953b757f7 /virt/kvm/iommu.c
parent13e7a8e846c2ea38a552b986ea49332f965bbb7a (diff)
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powerpc: Implement PPR save/restore
[PATCH 6/6] powerpc: Implement PPR save/restore When the task enters in to kernel space, the user defined priority (PPR) will be saved in to PACA at the beginning of first level exception vector and then copy from PACA to thread_info in second level vector. PPR will be restored from thread_info before exits the kernel space. P7/P8 temporarily raises the thread priority to higher level during exception until the program executes HMT_* calls. But it will not modify PPR register. So we save PPR value whenever some register is available to use and then calls HMT_MEDIUM to increase the priority. This feature supports on P7 or later processors. We save/ restore PPR for all exception vectors except system call entry. GLIBC will be saving / restore for system calls. So the default PPR value (3) will be set for the system call exit when the task returned to the user space. Signed-off-by: Haren Myneni <haren@us.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'virt/kvm/iommu.c')
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