From ca7d58f375c650cf36900cb1da1ca2cc99b13393 Mon Sep 17 00:00:00 2001 From: Xiao Guangrong Date: Wed, 13 Jul 2011 14:31:08 +0800 Subject: [PATCH] KVM: x86: fix broken read emulation spans a page boundary If the range spans a page boundary, the mmio access can be broke, fix it as write emulation. And we already get the guest physical address, so use it to read guest data directly to avoid walking guest page table again Signed-off-by: Xiao Guangrong Signed-off-by: Avi Kivity --- arch/x86/kvm/x86.c | 39 +++++++++++++++++++++++++++++++-------- 1 file changed, 31 insertions(+), 8 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 84a28ea45fa4..1453248723eb 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4045,13 +4045,12 @@ static int vcpu_mmio_gva_to_gpa(struct kvm_vcpu *vcpu, unsigned long gva, return 0; } -static int emulator_read_emulated(struct x86_emulate_ctxt *ctxt, - unsigned long addr, - void *val, - unsigned int bytes, - struct x86_exception *exception) +static int emulator_read_emulated_onepage(unsigned long addr, + void *val, + unsigned int bytes, + struct x86_exception *exception, + struct kvm_vcpu *vcpu) { - struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt); gpa_t gpa; int handled, ret; @@ -4071,8 +4070,7 @@ static int emulator_read_emulated(struct x86_emulate_ctxt *ctxt, if (ret) goto mmio; - if (kvm_read_guest_virt(ctxt, addr, val, bytes, exception) - == X86EMUL_CONTINUE) + if (!kvm_read_guest(vcpu->kvm, gpa, val, bytes)) return X86EMUL_CONTINUE; mmio: @@ -4101,6 +4099,31 @@ mmio: return X86EMUL_IO_NEEDED; } +static int emulator_read_emulated(struct x86_emulate_ctxt *ctxt, + unsigned long addr, + void *val, + unsigned int bytes, + struct x86_exception *exception) +{ + struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt); + + /* Crossing a page boundary? */ + if (((addr + bytes - 1) ^ addr) & PAGE_MASK) { + int rc, now; + + now = -addr & ~PAGE_MASK; + rc = emulator_read_emulated_onepage(addr, val, now, exception, + vcpu); + if (rc != X86EMUL_CONTINUE) + return rc; + addr += now; + val += now; + bytes -= now; + } + return emulator_read_emulated_onepage(addr, val, bytes, exception, + vcpu); +} + int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa, const void *val, int bytes) { -- 2.39.5