diff options
| author | Sean Christopherson <seanjc@google.com> | 2025-06-13 12:39:22 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2025-06-24 12:20:16 -0700 |
| commit | 0b6f4a5f0878c410677a8201c48127fda0bfd843 (patch) | |
| tree | 79263aa1c0c25e404647547d17a4c7aebb206aab | |
| parent | 48f15f624189762e7ff2d95bcbb68e21c2d56077 (diff) | |
KVM: x86/hyper-v: Use preallocated per-vCPU buffer for de-sparsified vCPU masks
Use a preallocated per-vCPU bitmap for tracking the unpacked set of vCPUs
being targeted for Hyper-V's paravirt TLB flushing. If KVM_MAX_NR_VCPUS
is set to 4096 (which is allowed even for MAXSMP=n builds), putting the
vCPU mask on-stack pushes kvm_hv_flush_tlb() past the default FRAME_WARN
limit.
arch/x86/kvm/hyperv.c:2001:12: error: stack frame size (1288) exceeds limit (1024)
in 'kvm_hv_flush_tlb' [-Werror,-Wframe-larger-than]
2001 | static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
| ^
1 error generated.
Note, sparse_banks was given the same treatment by commit 7d5e88d301f8
("KVM: x86: hyper-v: Use preallocated buffer in 'struct kvm_vcpu_hv'
instead of on-stack 'sparse_banks'"), for the exact same reason.
Reported-by: Abinash Lalotra <abinashsinghlalotra@gmail.com>
Closes: https://lore.kernel.org/all/20250613111023.786265-1-abinashsinghlalotra@gmail.com
Link: https://lore.kernel.org/all/aEylI-O8kFnFHrOH@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 7 | ||||
| -rw-r--r-- | arch/x86/kvm/hyperv.c | 2 |
2 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index b4a391929cdb..ee43615d96d8 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -700,8 +700,13 @@ struct kvm_vcpu_hv { struct kvm_vcpu_hv_tlb_flush_fifo tlb_flush_fifo[HV_NR_TLB_FLUSH_FIFOS]; - /* Preallocated buffer for handling hypercalls passing sparse vCPU set */ + /* + * Preallocated buffers for handling hypercalls that pass sparse vCPU + * sets (for high vCPU counts, they're too large to comfortably fit on + * the stack). + */ u64 sparse_banks[HV_MAX_SPARSE_VCPU_BANKS]; + DECLARE_BITMAP(vcpu_mask, KVM_MAX_VCPUS); struct hv_vp_assist_page vp_assist_page; diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 24f0318c50d7..75221a11e15e 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -2001,11 +2001,11 @@ out_flush_all: static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) { struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); + unsigned long *vcpu_mask = hv_vcpu->vcpu_mask; u64 *sparse_banks = hv_vcpu->sparse_banks; struct kvm *kvm = vcpu->kvm; struct hv_tlb_flush_ex flush_ex; struct hv_tlb_flush flush; - DECLARE_BITMAP(vcpu_mask, KVM_MAX_VCPUS); struct kvm_vcpu_hv_tlb_flush_fifo *tlb_flush_fifo; /* * Normally, there can be no more than 'KVM_HV_TLB_FLUSH_FIFO_SIZE' |