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SUSE:SLE-12-SP3:GA
xen.8425
5aec744a-5-x86-xpti-no-global-pages.patch
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File 5aec744a-5-x86-xpti-no-global-pages.patch of Package xen.8425
From d543fa409358a9128d3629dcb28daae28c2d150f Mon Sep 17 00:00:00 2001 From: Juergen Gross <jgross@suse.com> Date: Thu, 26 Apr 2018 13:33:14 +0200 Subject: [PATCH] xen/x86: disable global pages for domains with XPTI active Instead of flushing the TLB from global pages when switching address spaces with XPTI being active just disable global pages via %cr4 completely when a domain subject to XPTI is active. This avoids the need for extra TLB flushes as loading %cr3 will remove all TLB entries. In order to avoid states with cr3/cr4 having inconsistent values (e.g. global pages being activated while cr3 already specifies a XPTI address space) move loading of the new cr4 value to write_ptbase() (actually to switch_cr3_cr4() called by write_ptbase()). This requires to use switch_cr3_cr4() instead of write_ptbase() when building dom0 in order to avoid setting cr4 with cr4.smap set. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> --- a/xen/arch/x86/domain.c +++ b/xen/arch/x86/domain.c @@ -1403,7 +1403,6 @@ static void paravirt_ctxt_switch_from(st static void paravirt_ctxt_switch_to(struct vcpu *v) { root_pgentry_t *root_pgt = this_cpu(root_pgt); - unsigned long cr4; set_int80_direct_trap(v); switch_kernel_stack(v); @@ -1413,10 +1412,6 @@ static void paravirt_ctxt_switch_to(stru l4e_from_page(v->domain->arch.perdomain_l3_pg, __PAGE_HYPERVISOR); - cr4 = pv_guest_cr4_to_real_cr4(v); - if ( unlikely(cr4 != read_cr4()) ) - write_cr4(cr4); - if ( unlikely(v->arch.debugreg[7] & DR7_ACTIVE_MASK) ) { write_debugreg(0, v->arch.debugreg[0]); --- a/xen/arch/x86/domain_build.c +++ b/xen/arch/x86/domain_build.c @@ -776,7 +776,7 @@ int __init construct_dom0( update_cr3(v); /* We run on dom0's page tables for the final part of the build process. */ - write_ptbase(v); + switch_cr3_cr4(v->arch.cr3, read_cr4()); mapcache_override_current(v); /* Copy the OS image and free temporary buffer. */ @@ -796,7 +796,7 @@ int __init construct_dom0( (parms.virt_hypercall >= v_end) ) { mapcache_override_current(NULL); - write_ptbase(current); + switch_cr3_cr4(current->arch.cr3, read_cr4()); printk("Invalid HYPERCALL_PAGE field in ELF notes.\n"); rc = -1; goto out; @@ -1042,7 +1042,7 @@ int __init construct_dom0( /* Return to idle domain's page tables. */ mapcache_override_current(NULL); - write_ptbase(current); + switch_cr3_cr4(current->arch.cr3, read_cr4()); update_domain_wallclock_time(d); --- a/xen/arch/x86/efi/runtime.c +++ b/xen/arch/x86/efi/runtime.c @@ -104,7 +104,7 @@ struct efi_rs_state efi_rs_enter(void) asm volatile ( "lgdt %0" : : "m" (gdt_desc) ); } - switch_cr3(virt_to_maddr(efi_l4_pgtable)); + switch_cr3_cr4(virt_to_maddr(efi_l4_pgtable), read_cr4()); return state; } @@ -113,7 +113,7 @@ void efi_rs_leave(struct efi_rs_state *s { if ( !state->cr3 ) return; - switch_cr3(state->cr3); + switch_cr3_cr4(state->cr3, read_cr4()); if ( is_pv_vcpu(current) && !is_idle_vcpu(current) ) { struct desc_ptr gdt_desc = { --- a/xen/arch/x86/flushtlb.c +++ b/xen/arch/x86/flushtlb.c @@ -91,7 +91,7 @@ static void do_tlb_flush(void) post_flush(t); } -void switch_cr3(unsigned long cr3) +void switch_cr3_cr4(unsigned long cr3, unsigned long cr4) { unsigned long flags; u32 t; @@ -103,13 +103,23 @@ void switch_cr3(unsigned long cr3) #ifdef USER_MAPPINGS_ARE_GLOBAL { - unsigned long cr4 = read_cr4(); - write_cr4(cr4 & ~X86_CR4_PGE); + unsigned long old_cr4 = read_cr4(); + + if ( old_cr4 & X86_CR4_PGE ) + { + old_cr4 = cr4 & ~X86_CR4_PGE; + write_cr4(old_cr4); + } + write_cr3(cr3); - write_cr4(cr4); + + if ( old_cr4 != cr4 ) + write_cr4(cr4); } #else write_cr3(cr3); + if ( read_cr4() != cr4 ) + write_cr4(cr4); #endif post_flush(t); --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -499,20 +499,28 @@ void make_cr3(struct vcpu *v, unsigned l void write_ptbase(struct vcpu *v) { struct cpu_info *cpu_info = get_cpu_info(); + unsigned long new_cr4; + + new_cr4 = (is_pv_vcpu(v) && !is_idle_vcpu(v)) + ? pv_guest_cr4_to_real_cr4(v) + : ((read_cr4() & ~X86_CR4_TSD) | X86_CR4_PGE); if ( is_pv_vcpu(v) && v->domain->arch.pv_domain.xpti ) { cpu_info->root_pgt_changed = 1; cpu_info->pv_cr3 = __pa(this_cpu(root_pgt)); - switch_cr3(v->arch.cr3); + switch_cr3_cr4(v->arch.cr3, new_cr4); } else { - /* Make sure to clear xen_cr3 before pv_cr3; switch_cr3() serializes. */ + /* Make sure to clear xen_cr3 before pv_cr3. */ cpu_info->xen_cr3 = 0; - switch_cr3(v->arch.cr3); + /* switch_cr3_cr4() serializes. */ + switch_cr3_cr4(v->arch.cr3, new_cr4); cpu_info->pv_cr3 = 0; } + + ASSERT(is_pv_vcpu(v) || read_cr4() == mmu_cr4_features); } /* --- a/xen/include/asm-x86/asm_defns.h +++ b/xen/include/asm-x86/asm_defns.h @@ -81,13 +81,8 @@ void ret_from_intr(void); GET_STACK_BASE(reg); \ __GET_CURRENT(reg) -.macro write_cr3 val:req, tmp1:req, tmp2:req - mov %cr4, %\tmp1 - mov %\tmp1, %\tmp2 - and $~X86_CR4_PGE, %\tmp1 - mov %\tmp1, %cr4 +.macro write_cr3 val:req, tmp1, tmp2 mov %\val, %cr3 - mov %\tmp2, %cr4 .endm #ifndef NDEBUG --- a/xen/include/asm-x86/domain.h +++ b/xen/include/asm-x86/domain.h @@ -504,8 +504,9 @@ unsigned long pv_guest_cr4_fixup(const s #define pv_guest_cr4_to_real_cr4(v) \ (((v)->arch.pv_vcpu.ctrlreg[4] \ | (mmu_cr4_features \ - & (X86_CR4_PGE | X86_CR4_PSE | X86_CR4_SMEP | \ + & (X86_CR4_PSE | X86_CR4_SMEP | \ X86_CR4_OSXSAVE | X86_CR4_FSGSBASE)) \ + | ((v)->domain->arch.pv_domain.xpti ? 0 : X86_CR4_PGE) \ | ((v)->domain->arch.vtsc ? X86_CR4_TSD : 0)) \ & ~X86_CR4_DE) #define real_cr4_to_pv_guest_cr4(c) \ --- a/xen/include/asm-x86/flushtlb.h +++ b/xen/include/asm-x86/flushtlb.h @@ -84,7 +84,7 @@ static inline unsigned long read_cr3(voi } /* Write pagetable base and implicitly tick the tlbflush clock. */ -void switch_cr3(unsigned long cr3); +void switch_cr3_cr4(unsigned long cr3, unsigned long cr4); /* flush_* flag fields: */ /*
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