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KVM: nVMX: Check GUEST_DR7 on vmentry of nested guests

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According to section "Checks on Guest Control Registers, Debug Registers, and
and MSRs" in Intel SDM vol 3C, the following checks are performed on vmentry
of nested guests:

    If the "load debug controls" VM-entry control is 1, bits 63:32 in the DR7
    field must be 0.

In KVM, GUEST_DR7 is set prior to the vmcs02 VM-entry by kvm_set_dr() and the
latter synthesizes a #GP if any bit in the high dword in the former is set.
Hence this field needs to be checked in software.

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Karl Heubaum <karl.heubaum@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Krish Sadhukhan 2020-01-15 19:54:32 -05:00 committed by Paolo Bonzini
parent e174bb9483
commit b91991bf6b
3 changed files with 11 additions and 1 deletions
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4
arch/x86/kvm/vmx/nested.c
View File

@ -2887,6 +2887,10 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
CC(!nested_guest_cr4_valid(vcpu, vmcs12->guest_cr4)))
return -EINVAL;
if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS) &&
CC(!kvm_dr7_valid(vmcs12->guest_dr7)))
return -EINVAL;
if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PAT) &&
CC(!kvm_pat_valid(vmcs12->guest_ia32_pat)))
return -EINVAL;

2
arch/x86/kvm/x86.c
View File

@ -1082,7 +1082,7 @@ static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val)
case 5:
/* fall through */
default: /* 7 */
if (val & 0xffffffff00000000ULL)
if (!kvm_dr7_valid(val))
return -1; /* #GP */
vcpu->arch.dr7 = (val & DR7_VOLATILE) | DR7_FIXED_1;
kvm_update_dr7(vcpu);

6
arch/x86/kvm/x86.h
View File

@ -357,6 +357,12 @@ static inline bool kvm_pat_valid(u64 data)
return (data | ((data & 0x0202020202020202ull) << 1)) == data;
}
static inline bool kvm_dr7_valid(unsigned long data)
{
/* Bits [63:32] are reserved */
return !(data >> 32);
}
void kvm_load_guest_xsave_state(struct kvm_vcpu *vcpu);
void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu);
u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu);