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Commit bac15531 authored Jan 26, 2015 by Nadav Amit Committed by Paolo Bonzini Jan 26, 2015

KVM: x86: 32-bit wraparound read/write not emulated correctly

If we got a wraparound of 32-bit operand, and the limit is 0xffffffff, read and
writes should be successful. It just needs to be done in two segments.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 2b42fce6

arch/x86/kvm/emulate.c

+7 −3

Original line number	Diff line number	Diff line
		@@ -684,9 +684,13 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
		}
		if (addr.ea > lim)
		goto bad;
		*max_size = min_t(u64, ~0u, (u64)lim + 1 - addr.ea);
		if (lim == 0xffffffff)
		*max_size = ~0u;
		else {
		*max_size = (u64)lim + 1 - addr.ea;
		if (size > *max_size)
		goto bad;
		}
		la &= (u32)-1;
		break;
		}

arch/x86/kvm/x86.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -4495,6 +4495,8 @@ int emulator_read_write(struct x86_emulate_ctxt *ctxt, unsigned long addr,
		if (rc != X86EMUL_CONTINUE)
		return rc;
		addr += now;
		if (ctxt->mode != X86EMUL_MODE_PROT64)
		addr = (u32)addr;
		val += now;
		bytes -= now;
		}