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KVM: emulator: more strict rsm checks.

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Don't ignore return values in rsm_load_state_64/32 to avoid
loading invalid state from SMM state area if it was tampered with
by the guest.

This is primarly intended to avoid letting guest set bits in EFER
(like EFER.SVME when nesting is disabled) by manipulating SMM save area.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200827171145.374620-8-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Maxim Levitsky 2020-08-27 20:11:44 +03:00 committed by Paolo Bonzini
parent 3ebb5d2617
commit 37f66bbef0
1 changed files with 17 additions and 5 deletions
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22
arch/x86/kvm/emulate.c
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@ -2505,9 +2505,14 @@ static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt,
*reg_write(ctxt, i) = GET_SMSTATE(u32, smstate, 0x7fd0 + i * 4);
val = GET_SMSTATE(u32, smstate, 0x7fcc);
ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1);
if (ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1))
return X86EMUL_UNHANDLEABLE;
val = GET_SMSTATE(u32, smstate, 0x7fc8);
ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1);
if (ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1))
return X86EMUL_UNHANDLEABLE;
selector = GET_SMSTATE(u32, smstate, 0x7fc4);
set_desc_base(&desc, GET_SMSTATE(u32, smstate, 0x7f64));
@ -2560,16 +2565,23 @@ static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt,
ctxt->eflags = GET_SMSTATE(u32, smstate, 0x7f70) | X86_EFLAGS_FIXED;
val = GET_SMSTATE(u32, smstate, 0x7f68);
ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1);
if (ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1))
return X86EMUL_UNHANDLEABLE;
val = GET_SMSTATE(u32, smstate, 0x7f60);
ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1);
if (ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1))
return X86EMUL_UNHANDLEABLE;
cr0 = GET_SMSTATE(u64, smstate, 0x7f58);
cr3 = GET_SMSTATE(u64, smstate, 0x7f50);
cr4 = GET_SMSTATE(u64, smstate, 0x7f48);
ctxt->ops->set_smbase(ctxt, GET_SMSTATE(u32, smstate, 0x7f00));
val = GET_SMSTATE(u64, smstate, 0x7ed0);
ctxt->ops->set_msr(ctxt, MSR_EFER, val & ~EFER_LMA);
if (ctxt->ops->set_msr(ctxt, MSR_EFER, val & ~EFER_LMA))
return X86EMUL_UNHANDLEABLE;
selector = GET_SMSTATE(u32, smstate, 0x7e90);
rsm_set_desc_flags(&desc, GET_SMSTATE(u32, smstate, 0x7e92) << 8);