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authorMarc Zyngier <marc.zyngier@arm.com>2017-10-23 18:11:19 +0200
committerChristoffer Dall <christoffer.dall@linaro.org>2018-01-08 15:20:45 +0100
commitd0e22b4ac3ba23c611739f554392bf5e217df49f (patch)
tree33dd9a41741e6d8b653de9d715b6b277a2424c63 /virt
parentarm64: KVM: PTE/PMD S2 XN bit definition (diff)
downloadlinux-d0e22b4ac3ba23c611739f554392bf5e217df49f.tar.xz
linux-d0e22b4ac3ba23c611739f554392bf5e217df49f.zip
KVM: arm/arm64: Limit icache invalidation to prefetch aborts
We've so far eagerly invalidated the icache, no matter how the page was faulted in (data or prefetch abort). But we can easily track execution by setting the XN bits in the S2 page tables, get the prefetch abort at HYP and perform the icache invalidation at that time only. As for most VMs, the instruction working set is pretty small compared to the data set, this is likely to save some traffic (specially as the invalidation is broadcast). Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/arm/mmu.c19
1 files changed, 15 insertions, 4 deletions
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 2174244f6317..0417c8e2a81c 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1292,7 +1292,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
unsigned long fault_status)
{
int ret;
- bool write_fault, writable, hugetlb = false, force_pte = false;
+ bool write_fault, exec_fault, writable, hugetlb = false, force_pte = false;
unsigned long mmu_seq;
gfn_t gfn = fault_ipa >> PAGE_SHIFT;
struct kvm *kvm = vcpu->kvm;
@@ -1304,7 +1304,10 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
unsigned long flags = 0;
write_fault = kvm_is_write_fault(vcpu);
- if (fault_status == FSC_PERM && !write_fault) {
+ exec_fault = kvm_vcpu_trap_is_iabt(vcpu);
+ VM_BUG_ON(write_fault && exec_fault);
+
+ if (fault_status == FSC_PERM && !write_fault && !exec_fault) {
kvm_err("Unexpected L2 read permission error\n");
return -EFAULT;
}
@@ -1398,7 +1401,11 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
kvm_set_pfn_dirty(pfn);
}
clean_dcache_guest_page(vcpu, pfn, PMD_SIZE);
- invalidate_icache_guest_page(vcpu, pfn, PMD_SIZE);
+
+ if (exec_fault) {
+ new_pmd = kvm_s2pmd_mkexec(new_pmd);
+ invalidate_icache_guest_page(vcpu, pfn, PMD_SIZE);
+ }
ret = stage2_set_pmd_huge(kvm, memcache, fault_ipa, &new_pmd);
} else {
@@ -1410,7 +1417,11 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
mark_page_dirty(kvm, gfn);
}
clean_dcache_guest_page(vcpu, pfn, PAGE_SIZE);
- invalidate_icache_guest_page(vcpu, pfn, PAGE_SIZE);
+
+ if (exec_fault) {
+ new_pte = kvm_s2pte_mkexec(new_pte);
+ invalidate_icache_guest_page(vcpu, pfn, PAGE_SIZE);
+ }
ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte, flags);
}