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arm/arm64: KVM: Implement Stage-2 page aging

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Until now, KVM/arm didn't care much for page aging (who was swapping
anyway?), and simply provided empty hooks to the core KVM code. With
server-type systems now being available, things are quite different.

This patch implements very simple support for page aging, by clearing
the Access flag in the Stage-2 page tables. On access fault, the current
fault handling will write the PTE or PMD again, putting the Access flag
back on.

It should be possible to implement a much faster handling for Access
faults, but that's left for a later patch.

With this in place, performance in VMs is degraded much more gracefully.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This commit is contained in:
Marc Zyngier
2015-03-12 18:16:51 +00:00
committed by Christoffer Dall
parent 1d2ebaccc7
commit 35307b9a5f
7 changed files with 104 additions and 23 deletions
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1
arch/arm/include/asm/kvm_arm.h
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@@ -185,6 +185,7 @@
#define HSR_COND (0xfU << HSR_COND_SHIFT)
#define FSC_FAULT (0x04)
#define FSC_ACCESS (0x08)
#define FSC_PERM (0x0c)
/* Hyp Prefetch Fault Address Register (HPFAR/HDFAR) */