[PATCH 5.16 0864/1017] KVM: x86: hyper-v: Fix the maximum number of sparse banks for XMM fast TLB flush hypercalls

Greg Kroah-Hartman
2022-04-05T10:17:05Z

From: Vitaly Kuznetsov <vkuznets@redhat.com>

commit 7321f47eada53a395fb3086d49297eebb19e8e58 upstream.

When TLB flush hypercalls (HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}_EX are
issued in 'XMM fast' mode, the maximum number of allowed sparse_banks is
not 'HV_HYPERCALL_MAX_XMM_REGISTERS - 1' (5) but twice as many (10) as each
XMM register is 128 bit long and can hold two 64 bit long banks.

Cc: stable@vger.kernel.org # 5.14.x
Fixes: 5974565bc26d ("KVM: x86: kvm_hv_flush_tlb use inputs from XMM registers")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220222154642.684285-4-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 | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1819,7 +1819,8 @@ static u64 kvm_hv_flush_tlb(struct kvm_v

if (!all_cpus) {
if (hc->fast) {
- if (sparse_banks_len > HV_HYPERCALL_MAX_XMM_REGISTERS - 1)
+ /* 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 += 2) {
sparse_banks[i] = sse128_lo(hc->xmm[i / 2 + 1]);