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MIPS: KVM: Fix preemptable kvm_mips_get_*_asid() calls 

There are a couple of places in KVM fault handling code which implicitly
use smp_processor_id() via kvm_mips_get_kernel_asid() and
kvm_mips_get_user_asid() from preemptable context. This is unsafe as a
preemption could cause the guest kernel ASID to be changed, resulting in
a host TLB entry being written with the wrong ASID.

Fix by disabling preemption around the kvm_mips_get_*_asid() call and
the corresponding kvm_mips_host_tlb_write().

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
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
James Hogan 2016-04-22 10:38:47 +01:00 committed by Paolo Bonzini
parent b45bacd2d0
commit f049729c05
1 changed files with 18 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
arch/mips/kvm/tlb.c
View File

@ -268,6 +268,7 @@ int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr,
int even;
struct kvm *kvm = vcpu->kvm;
const int flush_dcache_mask = 0;
int ret;
if (KVM_GUEST_KSEGX(badvaddr) != KVM_GUEST_KSEG0) {
kvm_err("%s: Invalid BadVaddr: %#lx\n", __func__, badvaddr);
@ -299,14 +300,18 @@ int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr,
pfn1 = kvm->arch.guest_pmap[gfn];
}
entryhi = (vaddr | kvm_mips_get_kernel_asid(vcpu));
entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) | (0x3 << 3) |
(1 << 2) | (0x1 << 1);
entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) | (0x3 << 3) |
(1 << 2) | (0x1 << 1);
return kvm_mips_host_tlb_write(vcpu, entryhi, entrylo0, entrylo1,
flush_dcache_mask);
preempt_disable();
entryhi = (vaddr | kvm_mips_get_kernel_asid(vcpu));
ret = kvm_mips_host_tlb_write(vcpu, entryhi, entrylo0, entrylo1,
flush_dcache_mask);
preempt_enable();
return ret;
}
EXPORT_SYMBOL_GPL(kvm_mips_handle_kseg0_tlb_fault);
@ -361,6 +366,7 @@ int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
struct kvm *kvm = vcpu->kvm;
kvm_pfn_t pfn0, pfn1;
int ret;
if ((tlb->tlb_hi & VPN2_MASK) == 0) {
pfn0 = 0;
@ -387,9 +393,6 @@ int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
*hpa1 = pfn1 << PAGE_SHIFT;
/* Get attributes from the Guest TLB */
entryhi = (tlb->tlb_hi & VPN2_MASK) | (KVM_GUEST_KERNEL_MODE(vcpu) ?
kvm_mips_get_kernel_asid(vcpu) :
kvm_mips_get_user_asid(vcpu));
entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) | (0x3 << 3) |
(tlb->tlb_lo0 & MIPS3_PG_D) | (tlb->tlb_lo0 & MIPS3_PG_V);
entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) | (0x3 << 3) |
@ -398,8 +401,15 @@ int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc,
tlb->tlb_lo0, tlb->tlb_lo1);
return kvm_mips_host_tlb_write(vcpu, entryhi, entrylo0, entrylo1,
tlb->tlb_mask);
preempt_disable();
entryhi = (tlb->tlb_hi & VPN2_MASK) | (KVM_GUEST_KERNEL_MODE(vcpu) ?
kvm_mips_get_kernel_asid(vcpu) :
kvm_mips_get_user_asid(vcpu));
ret = kvm_mips_host_tlb_write(vcpu, entryhi, entrylo0, entrylo1,
tlb->tlb_mask);
preempt_enable();
return ret;
}
EXPORT_SYMBOL_GPL(kvm_mips_handle_mapped_seg_tlb_fault);