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KVM: x86: Add checks for reserved-to-zero Hyper-V hypercall fields

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Add checks for the three fields in Hyper-V's hypercall params that must
be zero.  Per the TLFS, HV_STATUS_INVALID_HYPERCALL_INPUT is returned if
"A reserved bit in the specified hypercall input value is non-zero."

Note, some versions of the TLFS have an off-by-one bug for the last
reserved field, and define it as being bits 64:60.  See
https://github.com/MicrosoftDocs/Virtualization-Documentation/pull/1682.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211207220926.718794-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-12-07 22:09:26 +00:00 committed by Paolo Bonzini
parent 40421f38f6
commit 413af6601f
2 changed files with 11 additions and 0 deletions
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5
arch/x86/kvm/hyperv.c
View File

@ -2240,6 +2240,11 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
goto hypercall_complete;
}
if (unlikely(hc.param & HV_HYPERCALL_RSVD_MASK)) {
ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
goto hypercall_complete;
}
if (hc.fast && is_xmm_fast_hypercall(&hc)) {
if (unlikely(hv_vcpu->enforce_cpuid &&
!(hv_vcpu->cpuid_cache.features_edx &

6
include/asm-generic/hyperv-tlfs.h
View File

@ -184,11 +184,17 @@ enum HV_GENERIC_SET_FORMAT {
#define HV_HYPERCALL_FAST_BIT BIT(16)
#define HV_HYPERCALL_VARHEAD_OFFSET 17
#define HV_HYPERCALL_VARHEAD_MASK GENMASK_ULL(26, 17)
#define HV_HYPERCALL_RSVD0_MASK GENMASK_ULL(31, 27)
#define HV_HYPERCALL_REP_COMP_OFFSET 32
#define HV_HYPERCALL_REP_COMP_1 BIT_ULL(32)
#define HV_HYPERCALL_REP_COMP_MASK GENMASK_ULL(43, 32)
#define HV_HYPERCALL_RSVD1_MASK GENMASK_ULL(47, 44)
#define HV_HYPERCALL_REP_START_OFFSET 48
#define HV_HYPERCALL_REP_START_MASK GENMASK_ULL(59, 48)
#define HV_HYPERCALL_RSVD2_MASK GENMASK_ULL(63, 60)
#define HV_HYPERCALL_RSVD_MASK (HV_HYPERCALL_RSVD0_MASK | \
HV_HYPERCALL_RSVD1_MASK | \
HV_HYPERCALL_RSVD2_MASK)
/* hypercall status code */
#define HV_STATUS_SUCCESS 0