On 1/13/21 6:37 PM, Sean Christopherson wrote:
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 <sea...@google.com> --- arch/x86/kvm/svm/sev.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 23a4bead4a82..e71bc742d8da 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -56,9 +56,14 @@ struct enc_region { unsigned long size; };-static int sev_flush_asids(void)+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_sev_asid, min_asid); + if (pos >= max_asid) + return -EBUSY;/** DEACTIVATE will clear the WBINVD indicator causing DF_FLUSH to fail, @@ -80,14 +85,7 @@ static int sev_flush_asids(void) /* 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 */@@ -1323,10 +1321,10 @@ void sev_hardware_teardown(void) if (!sev_enabled) return;+ sev_flush_asids(0, max_sev_asid);
I guess you could have called __sev_recycle_asids(0, max_sev_asid) here and left things unchanged up above. It would do the extra bitmap_xor() and bitmap_zero() operations, though. What do you think?
Also, maybe a comment about not needing the bitmap lock because this is during teardown.
Thanks, Tom
+ bitmap_free(sev_asid_bitmap); bitmap_free(sev_reclaim_asid_bitmap); - - sev_flush_asids(); }int sev_cpu_init(struct svm_cpu_data *sd)
