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KVM: MIPS/T&E: Add lockless GVA access helpers

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Add helpers to allow for lockless direct access to the GVA space, by
changing the VCPU mode to READING_SHADOW_PAGE_TABLES for the duration of
the access. This allows asynchronous TLB flush requests in future
patches to safely trigger either a TLB flush before the direct GVA space
access, or a delay until the in-progress lockless direct access is
complete.

The kvm_trap_emul_gva_lockless_begin() and
kvm_trap_emul_gva_lockless_end() helpers take care of guarding the
direct GVA accesses, and kvm_trap_emul_gva_fault() tries to handle a
uaccess fault resulting from a flush having taken place.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
This commit is contained in:
James Hogan
2016-11-28 23:04:52 +00:00
parent 91737ea205
commit 1880afd605
3 changed files with 131 additions and 0 deletions
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15
arch/mips/include/asm/kvm_host.h
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@@ -243,6 +243,7 @@ enum emulation_result {
#define TLB_ASID(x) ((x).tlb_hi & KVM_ENTRYHI_ASID)
#define TLB_LO_IDX(x, va) (((va) >> PAGE_SHIFT) & 1)
#define TLB_IS_VALID(x, va) ((x).tlb_lo[TLB_LO_IDX(x, va)] & ENTRYLO_V)
#define TLB_IS_DIRTY(x, va) ((x).tlb_lo[TLB_LO_IDX(x, va)] & ENTRYLO_D)
#define TLB_HI_VPN2_HIT(x, y) ((TLB_VPN2(x) & ~(x).tlb_mask) == \
((y) & VPN2_MASK & ~(x).tlb_mask))
#define TLB_HI_ASID_HIT(x, y) (TLB_IS_GLOBAL(x) || \
@@ -640,6 +641,20 @@ pgd_t *kvm_pgd_alloc(void);
void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);
void kvm_trap_emul_invalidate_gva(struct kvm_vcpu *vcpu, unsigned long addr,
bool user);
void kvm_trap_emul_gva_lockless_begin(struct kvm_vcpu *vcpu);
void kvm_trap_emul_gva_lockless_end(struct kvm_vcpu *vcpu);
enum kvm_mips_fault_result {
KVM_MIPS_MAPPED = 0,
KVM_MIPS_GVA,
KVM_MIPS_GPA,
KVM_MIPS_TLB,
KVM_MIPS_TLBINV,
KVM_MIPS_TLBMOD,
};
enum kvm_mips_fault_result kvm_trap_emul_gva_fault(struct kvm_vcpu *vcpu,
unsigned long gva,
bool write);
/* Emulation */
int kvm_get_inst(u32 *opc, struct kvm_vcpu *vcpu, u32 *out);