From 469bb32b68d5a414fea293c17b532329c6dc9612 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 21 Apr 2021 19:11:25 -0700 Subject: [PATCH] KVM: SVM: Skip SEV cache flush if no ASIDs have been used Skip SEV's expensive WBINVD and DF_FLUSH if there are no SEV ASIDs waiting to be reclaimed, e.g. if SEV was never used. This "fixes" an issue where the DF_FLUSH fails during hardware teardown if the original SEV_INIT failed. Ideally, SEV wouldn't be marked as enabled in KVM if SEV_INIT fails, but that's a problem for another day. Signed-off-by: Sean Christopherson Message-Id: <20210422021125.3417167-16-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index fd3ffc1..a9d8d6aa 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -74,9 +74,15 @@ struct enc_region { unsigned long size; }; -static int sev_flush_asids(void) +/* Called with the sev_bitmap_lock held, or on shutdown */ +static int sev_flush_asids(int min_asid, int max_asid) { - int ret, error = 0; + int ret, pos, error = 0; + + /* Check if there are any ASIDs to reclaim before performing a flush */ + pos = find_next_bit(sev_reclaim_asid_bitmap, max_asid, min_asid); + if (pos >= max_asid) + return -EBUSY; /* * DEACTIVATE will clear the WBINVD indicator causing DF_FLUSH to fail, @@ -103,14 +109,7 @@ static inline bool is_mirroring_enc_context(struct kvm *kvm) /* Must be called with the sev_bitmap_lock held */ static bool __sev_recycle_asids(int min_asid, int max_asid) { - int pos; - - /* Check if there are any ASIDs to reclaim before performing a flush */ - pos = find_next_bit(sev_reclaim_asid_bitmap, max_sev_asid, min_asid); - if (pos >= max_asid) - return false; - - if (sev_flush_asids()) + if (sev_flush_asids(min_asid, max_asid)) return false; /* The flush process will flush all reclaimable SEV and SEV-ES ASIDs */ @@ -1897,12 +1896,14 @@ void sev_hardware_teardown(void) if (!sev_enabled) return; + /* No need to take sev_bitmap_lock, all VMs have been destroyed. */ + sev_flush_asids(0, max_sev_asid); + bitmap_free(sev_asid_bitmap); bitmap_free(sev_reclaim_asid_bitmap); + misc_cg_set_capacity(MISC_CG_RES_SEV, 0); misc_cg_set_capacity(MISC_CG_RES_SEV_ES, 0); - - sev_flush_asids(); } int sev_cpu_init(struct svm_cpu_data *sd) -- 2.7.4