On 09.07.14 00:59, Stewart Smith wrote:
Hi!
Thanks for review, much appreciated!
Alexander Graf <ag...@suse.de> writes:
On 08.07.14 07:06, Stewart Smith wrote:
@@ -1528,6 +1535,7 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
int i, need_vpa_update;
int srcu_idx;
struct kvm_vcpu *vcpus_to_update[threads_per_core];
+ phys_addr_t phy_addr, tmp;
Please put the variable declarations into the if () branch so that the
compiler can catch potential leaks :)
ack. will fix.
@@ -1590,9 +1598,48 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
srcu_idx = srcu_read_lock(&vc->kvm->srcu);
+ /* If we have a saved list of L2/L3, restore it */
+ if (cpu_has_feature(CPU_FTR_ARCH_207S) && vc->mpp_buffer) {
+ phy_addr = virt_to_phys((void *)vc->mpp_buffer);
+#if defined(CONFIG_PPC_4K_PAGES)
+ phy_addr = (phy_addr + 8*4096) & ~(8*4096);
get_free_pages() is automatically aligned to the order, no?
That's what Paul reckoned too, and then we've attempted to find anywhere
that documents that behaviour. Happen to be able to point to docs/source
that say this is part of API?
Phew - it's probably buried somewhere. I could only find this document
saying that we always get order-aligned allocations:
http://www.thehackademy.net/madchat/ebooks/Mem_virtuelle/linux-mm/zonealloc.html
Mel, do you happen to have any pointer to something that explicitly (or
even properly implicitly) says that get_free_pages() returns
order-aligned memory?
+#endif
+ tmp = phy_addr & PPC_MPPE_ADDRESS_MASK;
+ tmp = tmp | PPC_MPPE_WHOLE_TABLE;
+
+ /* For sanity, abort any 'save' requests in progress */
+ asm volatile(PPC_LOGMPP(R1) : : "r" (tmp));
+
+ /* Inititate a cache-load request */
+ mtspr(SPRN_MPPR, tmp);
+ }
In fact, this whole block up here could be a function, no?
It could, perfectly happy for it to be one. Will fix.
+
+ /* Allocate memory before switching out of guest so we don't
+ trash L2/L3 with memory allocation stuff */
+ if (cpu_has_feature(CPU_FTR_ARCH_207S) && !vc->mpp_buffer) {
+ vc->mpp_buffer = __get_free_pages(GFP_KERNEL|__GFP_ZERO,
+ MPP_BUFFER_ORDER);
get_order(64 * 1024)?
Also, why allocate it here and not on vcore creation?
There's also the possibility of saving/restorting part of the L3 cache
as well, and I was envisioning a future patch to this which checks a
flag in vcore (maybe exposed via sysfs or whatever mechanism is
applicable) if it should save/restore L2 or L2/L3, so thus it makes a
bit more sense allocating it there rather than elsewhere.
There's also no real reason to fail to create a vcore if we can't
allocate a buffer for L2/L3 cache contents - retrying later is perfectly
harmless.
If we failed during core creation just don't save/restore L2 cache
contents at all. I really prefer to have allocation and dealloction all
at init time - and such low order allocations will most likely succeed.
Let's leave the L3 cache bits for later when we know whether it actually
has an impact. I personally doubt it :).
Alex
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