From: Vitaly Kuznetsov vkuznets@redhat.com
commit 47d3e5cdfe607ec6883eb0faa7acf05b8cb3f92a upstream.
It has been proven on practice that at least Windows Server 2019 tries using HVCALL_SEND_IPI_EX in 'XMM fast' mode when it has more than 64 vCPUs and it needs to send an IPI to a vCPU > 63. Similarly to other XMM Fast hypercalls (HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}{,_EX}), this information is missing in TLFS as of 6.0b. Currently, KVM returns an error (HV_STATUS_INVALID_HYPERCALL_INPUT) and Windows crashes.
Note, HVCALL_SEND_IPI is a 'standard' fast hypercall (not 'XMM fast') as all its parameters fit into RDX:R8 and this is handled by KVM correctly.
Cc: stable@vger.kernel.org # 5.14.x: 3244867af8c0: KVM: x86: Ignore sparse banks size for an "all CPUs", non-sparse IPI req Cc: stable@vger.kernel.org # 5.14.x Fixes: d8f5537a8816 ("KVM: hyper-v: Advertise support for fast XMM hypercalls") Signed-off-by: Vitaly Kuznetsov vkuznets@redhat.com Message-Id: 20220222154642.684285-5-vkuznets@redhat.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/hyperv.c | 52 ++++++++++++++++++++++++++++++++------------------ 1 file changed, 34 insertions(+), 18 deletions(-)
--- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -1890,6 +1890,7 @@ static u64 kvm_hv_send_ipi(struct kvm_vc int sparse_banks_len; u32 vector; bool all_cpus; + int i;
if (hc->code == HVCALL_SEND_IPI) { if (!hc->fast) { @@ -1910,9 +1911,15 @@ static u64 kvm_hv_send_ipi(struct kvm_vc
trace_kvm_hv_send_ipi(vector, sparse_banks[0]); } else { - if (unlikely(kvm_read_guest(kvm, hc->ingpa, &send_ipi_ex, - sizeof(send_ipi_ex)))) - return HV_STATUS_INVALID_HYPERCALL_INPUT; + if (!hc->fast) { + if (unlikely(kvm_read_guest(kvm, hc->ingpa, &send_ipi_ex, + sizeof(send_ipi_ex)))) + return HV_STATUS_INVALID_HYPERCALL_INPUT; + } else { + send_ipi_ex.vector = (u32)hc->ingpa; + send_ipi_ex.vp_set.format = hc->outgpa; + send_ipi_ex.vp_set.valid_bank_mask = sse128_lo(hc->xmm[0]); + }
trace_kvm_hv_send_ipi_ex(send_ipi_ex.vector, send_ipi_ex.vp_set.format, @@ -1920,8 +1927,7 @@ static u64 kvm_hv_send_ipi(struct kvm_vc
vector = send_ipi_ex.vector; valid_bank_mask = send_ipi_ex.vp_set.valid_bank_mask; - sparse_banks_len = bitmap_weight(&valid_bank_mask, 64) * - sizeof(sparse_banks[0]); + sparse_banks_len = bitmap_weight(&valid_bank_mask, 64);
all_cpus = send_ipi_ex.vp_set.format == HV_GENERIC_SET_ALL;
@@ -1931,12 +1937,27 @@ static u64 kvm_hv_send_ipi(struct kvm_vc if (!sparse_banks_len) goto ret_success;
- if (kvm_read_guest(kvm, - hc->ingpa + offsetof(struct hv_send_ipi_ex, - vp_set.bank_contents), - sparse_banks, - sparse_banks_len)) - return HV_STATUS_INVALID_HYPERCALL_INPUT; + if (!hc->fast) { + if (kvm_read_guest(kvm, + hc->ingpa + offsetof(struct hv_send_ipi_ex, + vp_set.bank_contents), + sparse_banks, + sparse_banks_len * sizeof(sparse_banks[0]))) + return HV_STATUS_INVALID_HYPERCALL_INPUT; + } else { + /* + * The lower half of XMM0 is already consumed, each XMM holds + * two sparse banks. + */ + if (sparse_banks_len > (2 * HV_HYPERCALL_MAX_XMM_REGISTERS - 1)) + return HV_STATUS_INVALID_HYPERCALL_INPUT; + for (i = 0; i < sparse_banks_len; i++) { + if (i % 2) + sparse_banks[i] = sse128_lo(hc->xmm[(i + 1) / 2]); + else + sparse_banks[i] = sse128_hi(hc->xmm[i / 2]); + } + } }
check_and_send_ipi: @@ -2098,6 +2119,7 @@ static bool is_xmm_fast_hypercall(struct case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE: case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX: case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX: + case HVCALL_SEND_IPI_EX: return true; }
@@ -2265,14 +2287,8 @@ int kvm_hv_hypercall(struct kvm_vcpu *vc ret = kvm_hv_flush_tlb(vcpu, &hc); break; case HVCALL_SEND_IPI: - if (unlikely(hc.rep)) { - ret = HV_STATUS_INVALID_HYPERCALL_INPUT; - break; - } - ret = kvm_hv_send_ipi(vcpu, &hc); - break; case HVCALL_SEND_IPI_EX: - if (unlikely(hc.fast || hc.rep)) { + if (unlikely(hc.rep)) { ret = HV_STATUS_INVALID_HYPERCALL_INPUT; break; }