Add a module param, flush_on_reuse, to override skip_tlb_flush and skip_mmu_sync when performing a so called "fast cr3 switch", i.e. when reusing a cached root. The primary motiviation for the control is to provide a fallback mechanism in the event that TLB flushing and/or MMU sync bugs are exposed/introduced by upcoming changes to stop unconditionally flushing on nested VMX transitions. Suggested-by: Jim Mattson <jmattson@xxxxxxxxxx> Suggested-by: Junaid Shahid <junaids@xxxxxxxxxx> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> --- arch/x86/kvm/mmu/mmu.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 06e94ca59a2d..6a986b66c867 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -78,6 +78,9 @@ module_param_cb(nx_huge_pages_recovery_ratio, &nx_huge_pages_recovery_ratio_ops, &nx_huge_pages_recovery_ratio, 0644); __MODULE_PARM_TYPE(nx_huge_pages_recovery_ratio, "uint"); +static bool __read_mostly force_flush_and_sync_on_reuse; +module_param_named(flush_on_reuse, force_flush_and_sync_on_reuse, bool, 0644); + /* * When setting this variable to true it enables Two-Dimensional-Paging * where the hardware walks 2 page tables: @@ -4322,9 +4325,9 @@ static void __kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, */ kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu); - if (!skip_mmu_sync) + if (!skip_mmu_sync || force_flush_and_sync_on_reuse) kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); - if (!skip_tlb_flush) + if (!skip_tlb_flush || force_flush_and_sync_on_reuse) kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); /* -- 2.24.1
