From: Roger Pau Monné <[email protected]> We want to change per-domain mappings to be per-vCPU mappings. In preparation for that, we want to arrange that destroy_perdomain_mapping() work either with a single perdomain area, or with a per-vCPU perdomain area.
The remaining callers are already in a vCPU context, so we just need to change the parameter from a domain pointer to a vCPU pointer. Since we now have a specific vCPU in mind, we have the option of using the linear page table mapping rather than map-and-walk. As in populate_perdomain_mapping(), the linear page table fast path is keyed off this_cpu(pgtable_vcpu) matching the target vCPU, which is the conditional that implies "the linear mapping area points to v's per-domain area". Signed-off-by: Roger Pau Monné <[email protected]> Assisted-by: Claude Code:claude-fable-5, Claude Code:claude-opus-4-8 Signed-off-by: George Dunlap <[email protected]> --- Changes in v2: - Added to the series Changes since the previously posted version: - Key the fast path off pgtable_vcpu instead of current, matching populate_perdomain_mapping(), and drop the sync_local_execstate() call. - Also convert the pv_destroy_ldt() call, added by the stash-removal batch. - Reword and retitle for clarity (was: "x86/mm: switch destroy_perdomain_mapping() parameter from domain to vCPU"). --- xen/arch/x86/include/asm/mm.h | 2 +- xen/arch/x86/mm.c | 23 ++++++++++++++++++++++- xen/arch/x86/pv/descriptor-tables.c | 2 +- xen/arch/x86/pv/domain.c | 3 +-- xen/arch/x86/x86_64/mm.c | 2 +- 5 files changed, 26 insertions(+), 6 deletions(-) diff --git a/xen/arch/x86/include/asm/mm.h b/xen/arch/x86/include/asm/mm.h index 30eaec9179..9a8fda782e 100644 --- a/xen/arch/x86/include/asm/mm.h +++ b/xen/arch/x86/include/asm/mm.h @@ -605,7 +605,7 @@ int create_perdomain_mapping(struct domain *d, unsigned long va, void populate_perdomain_mapping(const struct vcpu *v, unsigned long va, const mfn_t *mfn, unsigned int nr, unsigned int flags); -void destroy_perdomain_mapping(struct domain *d, unsigned long va, +void destroy_perdomain_mapping(const struct vcpu *v, unsigned long va, unsigned int nr); void free_perdomain_mappings(struct domain *d); diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 48d1b427c5..fc524ef0c3 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -6456,10 +6456,11 @@ void populate_perdomain_mapping(const struct vcpu *v, unsigned long va, local_irq_restore(irq_flags); } -void destroy_perdomain_mapping(struct domain *d, unsigned long va, +void destroy_perdomain_mapping(const struct vcpu *v, unsigned long va, unsigned int nr) { const l3_pgentry_t *l3tab, *pl3e; + const struct domain *d = v->domain; ASSERT(va >= PERDOMAIN_VIRT_START && va < PERDOMAIN_VIRT_SLOT(PERDOMAIN_SLOTS)); @@ -6468,6 +6469,26 @@ void destroy_perdomain_mapping(struct domain *d, unsigned long va, if ( !d->arch.perdomain_l3_pg ) return; + if ( likely(this_cpu(pgtable_vcpu) == v) ) + { + l1_pgentry_t *pl1e; + + /* + * Fast path: v's page-tables are loaded on this pCPU, so the L1 + * entries can be zapped using the recursive linear mappings. + */ + pl1e = &__linear_l1_table[l1_linear_offset(va)]; + + for ( ; nr--; pl1e++ ) + { + if ( perdomain_l1e_needs_freeing(*pl1e) ) + free_domheap_page(l1e_get_page(*pl1e)); + l1e_write(pl1e, l1e_empty()); + } + + return; + } + l3tab = __map_domain_page(d->arch.perdomain_l3_pg); pl3e = l3tab + l3_table_offset(va); diff --git a/xen/arch/x86/pv/descriptor-tables.c b/xen/arch/x86/pv/descriptor-tables.c index 261bf29c90..0c1ea4ce3a 100644 --- a/xen/arch/x86/pv/descriptor-tables.c +++ b/xen/arch/x86/pv/descriptor-tables.c @@ -27,7 +27,7 @@ bool pv_destroy_ldt(struct vcpu *v) ASSERT(v == current || !vcpu_cpu_dirty(v)); - destroy_perdomain_mapping(v->domain, LDT_VIRT_START(v), nr_frames); + destroy_perdomain_mapping(v, LDT_VIRT_START(v), nr_frames); for ( i = 0; i < nr_frames; i++ ) { diff --git a/xen/arch/x86/pv/domain.c b/xen/arch/x86/pv/domain.c index b936ca9b26..40b834e1a4 100644 --- a/xen/arch/x86/pv/domain.c +++ b/xen/arch/x86/pv/domain.c @@ -319,8 +319,7 @@ static int pv_create_gdt_ldt_l1tab(struct vcpu *v) static void pv_destroy_gdt_ldt_l1tab(struct vcpu *v) { - destroy_perdomain_mapping(v->domain, GDT_VIRT_START(v), - 1U << GDT_LDT_VCPU_SHIFT); + destroy_perdomain_mapping(v, GDT_VIRT_START(v), 1U << GDT_LDT_VCPU_SHIFT); } void pv_vcpu_destroy(struct vcpu *v) diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c index ffeda06e08..aa74acec82 100644 --- a/xen/arch/x86/x86_64/mm.c +++ b/xen/arch/x86/x86_64/mm.c @@ -738,7 +738,7 @@ int setup_compat_arg_xlat(struct vcpu *v) void free_compat_arg_xlat(struct vcpu *v) { - destroy_perdomain_mapping(v->domain, ARG_XLAT_START(v), + destroy_perdomain_mapping(v, ARG_XLAT_START(v), PFN_UP(COMPAT_ARG_XLAT_SIZE)); } -- 2.55.0
