kernel/linux.git/arch/powerpc/kvm/e500mc.c, branch linux-4.4.y

powerpc: Replace __get_cpu_var uses

2014-11-03T01:12:32+00:00

This still has not been merged and now powerpc is the only arch that does not have this change. Sorry about missing linuxppc-dev before. V2->V2 - Fix up to work against 3.18-rc1 __get_cpu_var() is used for multiple purposes in the kernel source. One of them is address calculation via the form &__get_cpu_var(x). This calculates the address for the instance of the percpu variable of the current processor based on an offset. Other use cases are for storing and retrieving data from the current processors percpu area. __get_cpu_var() can be used as an lvalue when writing data or on the right side of an assignment. __get_cpu_var() is defined as : __get_cpu_var() always only does an address determination. However, store and retrieve operations could use a segment prefix (or global register on other platforms) to avoid the address calculation. this_cpu_write() and this_cpu_read() can directly take an offset into a percpu area and use optimized assembly code to read and write per cpu variables. This patch converts __get_cpu_var into either an explicit address calculation using this_cpu_ptr() or into a use of this_cpu operations that use the offset. Thereby address calculations are avoided and less registers are used when code is generated. At the end of the patch set all uses of __get_cpu_var have been removed so the macro is removed too. The patch set includes passes over all arches as well. Once these operations are used throughout then specialized macros can be defined in non -x86 arches as well in order to optimize per cpu access by f.e. using a global register that may be set to the per cpu base. Transformations done to __get_cpu_var() 1. Determine the address of the percpu instance of the current processor. DEFINE_PER_CPU(int, y); int *x = &__get_cpu_var(y); Converts to int *x = this_cpu_ptr(&y); 2. Same as #1 but this time an array structure is involved. DEFINE_PER_CPU(int, y[20]); int *x = __get_cpu_var(y); Converts to int *x = this_cpu_ptr(y); 3. Retrieve the content of the current processors instance of a per cpu variable. DEFINE_PER_CPU(int, y); int x = __get_cpu_var(y) Converts to int x = __this_cpu_read(y); 4. Retrieve the content of a percpu struct DEFINE_PER_CPU(struct mystruct, y); struct mystruct x = __get_cpu_var(y); Converts to memcpy(&x, this_cpu_ptr(&y), sizeof(x)); 5. Assignment to a per cpu variable DEFINE_PER_CPU(int, y) __get_cpu_var(y) = x; Converts to __this_cpu_write(y, x); 6. Increment/Decrement etc of a per cpu variable DEFINE_PER_CPU(int, y); __get_cpu_var(y)++ Converts to __this_cpu_inc(y) Cc: Benjamin Herrenschmidt CC: Paul Mackerras Signed-off-by: Christoph Lameter [mpe: Fix build errors caused by set/or_softirq_pending(), and rework assignment in __set_breakpoint() to use memcpy().] Signed-off-by: Michael Ellerman

KVM: PPC: Book3E: Enable e6500 core

2014-09-22T08:11:35+00:00

Now that AltiVec and hardware thread support is in place enable e6500 core. Signed-off-by: Mihai Caraman Signed-off-by: Alexander Graf

KVM: PPC: e500mc: Add support for single threaded vcpus on e6500 core

2014-09-22T08:11:35+00:00

ePAPR represents hardware threads as cpu node properties in device tree. So with existing QEMU, hardware threads are simply exposed as vcpus with one hardware thread. The e6500 core shares TLBs between hardware threads. Without tlb write conditional instruction, the Linux kernel uses per core mechanisms to protect against duplicate TLB entries. The guest is unable to detect real siblings threads, so it can't use the TLB protection mechanism. An alternative solution is to use the hypervisor to allocate different lpids to guest's vcpus that runs simultaneous on real siblings threads. On systems with two threads per core this patch halves the size of the lpid pool that the allocator sees and use two lpids per VM. Use even numbers to speedup vcpu lpid computation with consecutive lpids per VM: vm1 will use lpids 2 and 3, vm2 lpids 4 and 5, and so on. Signed-off-by: Mihai Caraman [agraf: fix spelling] Signed-off-by: Alexander Graf

KVM: PPC: Book3E: Increase FPU laziness

2014-09-22T08:11:32+00:00

Increase FPU laziness by loading the guest state into the unit before entering the guest instead of doing it on each vcpu schedule. Without this improvement an interrupt may claim floating point corrupting guest state. Signed-off-by: Mihai Caraman Signed-off-by: Alexander Graf

KVM: PPC: BOOKE: Allow guest to change MSR_DE

2014-09-22T08:11:29+00:00

This patch changes the default behavior of MSRP_DEP, that is guest is not allowed to change the MSR_DE, to guest can change MSR_DE. When userspace is debugging guest then it override the default behavior and set MSRP_DEP. This stops guest to change MSR_DE when userspace is debugging guest. Signed-off-by: Bharat Bhushan Signed-off-by: Alexander Graf

KVM: PPC: Booke-hv: Add one reg interface for SPRG9

2014-07-28T13:23:15+00:00

We now support SPRG9 for guest, so also add a one reg interface for same Note: Changes are in bookehv code only as we do not have SPRG9 on booke-pr. Signed-off-by: Bharat Bhushan Signed-off-by: Alexander Graf

KVM: PPC: e500mc: Enhance tlb invalidation condition on vcpu schedule

2014-07-28T13:22:16+00:00

On vcpu schedule, the condition checked for tlb pollution is too loose. The tlb entries of a vcpu become polluted (vs stale) only when a different vcpu within the same logical partition runs in-between. Optimize the tlb invalidation condition keeping last_vcpu per logical partition id. With the new invalidation condition, a guest shows 4% performance improvement on P5020DS while running a memory stress application with the cpu oversubscribed, the other guest running a cpu intensive workload. Guest - old invalidation condition real 3.89 user 3.87 sys 0.01 Guest - enhanced invalidation condition real 3.75 user 3.73 sys 0.01 Host real 3.70 user 1.85 sys 0.00 The memory stress application accesses 4KB pages backed by 75% of available TLB0 entries: char foo[ENTRIES][4096] __attribute__ ((aligned (4096))); int main() { char bar; int i, j; for (i = 0; i < ITERATIONS; i++) for (j = 0; j < ENTRIES; j++) bar = foo[j][0]; return 0; } Signed-off-by: Mihai Caraman Reviewed-by: Scott Wood Signed-off-by: Alexander Graf

KVM: PPC: Add devname:kvm aliases for modules

2014-01-09T09:14:00+00:00

Systems that support automatic loading of kernel modules through device aliases should try and automatically load kvm when /dev/kvm gets opened. Add code to support that magic for all PPC kvm targets, even the ones that don't support modules yet. Signed-off-by: Alexander Graf

kvm: powerpc: book3s: Allow the HV and PR selection per virtual machine

2013-10-17T16:42:36+00:00

This moves the kvmppc_ops callbacks to be a per VM entity. This enables us to select HV and PR mode when creating a VM. We also allow both kvm-hv and kvm-pr kernel module to be loaded. To achieve this we move /dev/kvm ownership to kvm.ko module. Depending on which KVM mode we select during VM creation we take a reference count on respective module Signed-off-by: Aneesh Kumar K.V [agraf: fix coding style] Signed-off-by: Alexander Graf

kvm: powerpc: Add kvmppc_ops callback

2013-10-17T13:24:26+00:00

This patch add a new callback kvmppc_ops. This will help us in enabling both HV and PR KVM together in the same kernel. The actual change to enable them together is done in the later patch in the series. Signed-off-by: Aneesh Kumar K.V [agraf: squash in booke changes] Signed-off-by: Alexander Graf