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arm, arm64: KVM: allow forced dcache flush on page faults
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To allow handling of incoherent memslots in a subsequent patch, this
patch adds a paramater 'ipa_uncached' to cache_coherent_guest_page()
so that we can instruct it to flush the page's contents to DRAM even
if the guest has caching globally enabled.

Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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Laszlo Ersek authored and Marc Zyngier committed Nov 25, 2014
1 parent 1050dcd commit 840f4bf
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Showing 3 changed files with 13 additions and 6 deletions.
5 changes: 3 additions & 2 deletions arch/arm/include/asm/kvm_mmu.h
Original file line number Diff line number Diff line change
Expand Up @@ -161,9 +161,10 @@ static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu)
}

static inline void coherent_cache_guest_page(struct kvm_vcpu *vcpu, hva_t hva,
unsigned long size)
unsigned long size,
bool ipa_uncached)
{
if (!vcpu_has_cache_enabled(vcpu))
if (!vcpu_has_cache_enabled(vcpu) || ipa_uncached)
kvm_flush_dcache_to_poc((void *)hva, size);

/*
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9 changes: 7 additions & 2 deletions arch/arm/kvm/mmu.c
Original file line number Diff line number Diff line change
Expand Up @@ -852,6 +852,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
struct vm_area_struct *vma;
pfn_t pfn;
pgprot_t mem_type = PAGE_S2;
bool fault_ipa_uncached;

write_fault = kvm_is_write_fault(vcpu);
if (fault_status == FSC_PERM && !write_fault) {
Expand Down Expand Up @@ -918,22 +919,26 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
if (!hugetlb && !force_pte)
hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa);

fault_ipa_uncached = false;

if (hugetlb) {
pmd_t new_pmd = pfn_pmd(pfn, mem_type);
new_pmd = pmd_mkhuge(new_pmd);
if (writable) {
kvm_set_s2pmd_writable(&new_pmd);
kvm_set_pfn_dirty(pfn);
}
coherent_cache_guest_page(vcpu, hva & PMD_MASK, PMD_SIZE);
coherent_cache_guest_page(vcpu, hva & PMD_MASK, PMD_SIZE,
fault_ipa_uncached);
ret = stage2_set_pmd_huge(kvm, memcache, fault_ipa, &new_pmd);
} else {
pte_t new_pte = pfn_pte(pfn, mem_type);
if (writable) {
kvm_set_s2pte_writable(&new_pte);
kvm_set_pfn_dirty(pfn);
}
coherent_cache_guest_page(vcpu, hva, PAGE_SIZE);
coherent_cache_guest_page(vcpu, hva, PAGE_SIZE,
fault_ipa_uncached);
ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte,
pgprot_val(mem_type) == pgprot_val(PAGE_S2_DEVICE));
}
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5 changes: 3 additions & 2 deletions arch/arm64/include/asm/kvm_mmu.h
Original file line number Diff line number Diff line change
Expand Up @@ -243,9 +243,10 @@ static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu)
}

static inline void coherent_cache_guest_page(struct kvm_vcpu *vcpu, hva_t hva,
unsigned long size)
unsigned long size,
bool ipa_uncached)
{
if (!vcpu_has_cache_enabled(vcpu))
if (!vcpu_has_cache_enabled(vcpu) || ipa_uncached)
kvm_flush_dcache_to_poc((void *)hva, size);

if (!icache_is_aliasing()) { /* PIPT */
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