From e1604ea8270096e5bb15866a1db75fbe56a730c7 Mon Sep 17 00:00:00 2001 From: Ross Lagerwall Date: Mon, 23 Mar 2026 11:17:06 +0100 Subject: [PATCH] x86/hap: Defer NPT P2M TLB flushes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Like the EPT code, defer TLB flushes for NPT to reduce the number of flushes and avoid holding the P2M lock while flushing. This can substantially improve performance in some scenarios. The cases where the TLB needs to be flushed without deferring are already handled by the call to p2m_tlb_flush_sync() in p2m_free_ptp(). Suggested-by: Roger Pau Monne Signed-off-by: Ross Lagerwall Reviewed-by: Roger Pau Monné --- xen/arch/x86/mm/hap/hap.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c index a337752bf4..5ccb80bda5 100644 --- a/xen/arch/x86/mm/hap/hap.c +++ b/xen/arch/x86/mm/hap/hap.c @@ -814,15 +814,33 @@ static void cf_check hap_update_paging_modes(struct vcpu *v) static void cf_check hap_write_p2m_entry_post(struct p2m_domain *p2m, unsigned int oflags) { - struct domain *d = p2m->domain; + if ( !(oflags & _PAGE_PRESENT) ) + return; - if ( oflags & _PAGE_PRESENT ) + if ( unlikely(!p2m->defer_flush) ) + { + const struct domain *d = p2m->domain; + + ASSERT_UNREACHABLE(); guest_flush_tlb_mask(d, d->dirty_cpumask); + return; + } + + p2m->need_flush = true; +} + +static void cf_check +hap_p2m_tlb_flush(struct p2m_domain *p2m) +{ + const struct domain *d = p2m->domain; + + guest_flush_tlb_mask(d, d->dirty_cpumask); } void hap_p2m_init(struct p2m_domain *p2m) { p2m->write_p2m_entry_post = hap_write_p2m_entry_post; + p2m->tlb_flush = hap_p2m_tlb_flush; } static unsigned long cf_check hap_gva_to_gfn_real_mode(