Xen project Mailing List

[Xen-devel] [PATCH xen-4.6] xen: Remove CONFIG_X86_SUPERVISOR_MODE_KERNEL as x86_32 builds are unsupported

From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Date: Fri, 2 Jan 2015 19:12:23 +0000

Cc: Keir Fraser <keir@xxxxxxx>, Ian Campbell <ian.campbell@xxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Tim Deegan <tim@xxxxxxx>, Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxx>

Delivery-date: Fri, 02 Jan 2015 19:12:50 +0000

List-id: Xen developer discussion <xen-devel.lists.xen.org>

supervisor_mode_kernel was an x86_32-only feature which permitted a PV dom0 to run in ring 0, but at the expense of not being able to start any domUs. As the x86_32 Xen build has been removed from tree, removing the remaining supervisor_mode_kernel code. Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> CC: Keir Fraser <keir@xxxxxxx> CC: Jan Beulich <JBeulich@xxxxxxxx> CC: Ian Campbell <ian.campbell@xxxxxxxxxx> CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx> CC: Tim Deegan <tim@xxxxxxx> --- One complication is that PVH has reused XENFEAT_supervisor_mode_kernel with a modified meaning, and the Linux PVH code actively uses the flag as to indicate running as a PVH guest. This causes an discontinuity between PVH and HVM guests, both of which run their kernels with the PVH-taken meaning of XENFEAT_supervisor_mode_kernel. It also means that a dom0 kernel is unable to express "PVH-only" by requiring this feature, as a 64bit Xen will validly reject an attempt to require a 32bit-only Xen feature. Someone with more tuits than I currently have will need to see about untangling this as part of unifying the PVH and HVM guest types, preferably before the ABI is declared stable. --- xen/arch/x86/Rules.mk | 10 ---------- xen/arch/x86/domain.c | 3 --- xen/arch/x86/domain_build.c | 24 ++++++------------------ xen/common/domctl.c | 3 +-- xen/common/kernel.c | 2 -- xen/include/asm-arm/config.h | 2 -- xen/include/asm-x86/config.h | 6 ------ xen/include/asm-x86/desc.h | 10 ---------- 8 files changed, 7 insertions(+), 53 deletions(-) diff --git a/xen/arch/x86/Rules.mk b/xen/arch/x86/Rules.mk index 6775cb5..ef8c222 100644 --- a/xen/arch/x86/Rules.mk +++ b/xen/arch/x86/Rules.mk @@ -15,12 +15,6 @@ HAS_GDBSX := y HAS_PDX := y xenoprof := y -# -# If you change any of these configuration options then you must -# 'make clean' before rebuilding. -# -supervisor_mode_kernel ?= n - CFLAGS += -I$(BASEDIR)/include CFLAGS += -I$(BASEDIR)/include/asm-x86/mach-generic CFLAGS += -I$(BASEDIR)/include/asm-x86/mach-default @@ -34,10 +28,6 @@ $(call as-insn-check,CFLAGS,CC,"vmcall",-DHAVE_GAS_VMX) $(call as-insn-check,CFLAGS,CC,"invept (%rax)$$(comma)%rax",-DHAVE_GAS_EPT) $(call as-insn-check,CFLAGS,CC,"rdfsbase %rax",-DHAVE_GAS_FSGSBASE) -ifeq ($(supervisor_mode_kernel),y) -CFLAGS += -DCONFIG_X86_SUPERVISOR_MODE_KERNEL=1 -endif - x86 := y x86_32 := n x86_64 := y diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c index 11c7d9f..b699510 100644 --- a/xen/arch/x86/domain.c +++ b/xen/arch/x86/domain.c @@ -1726,9 +1726,6 @@ unsigned long hypercall_create_continuation( } else { - if ( supervisor_mode_kernel ) - regs->eip &= ~31; /* re-execute entire hypercall entry stub */ - for ( i = 0; *p != '\0'; i++ ) { arg = next_arg(p, args); diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c index 7993b17..7a912e9 100644 --- a/xen/arch/x86/domain_build.c +++ b/xen/arch/x86/domain_build.c @@ -1410,24 +1410,12 @@ int __init construct_dom0( paging_update_paging_modes(v); } - if ( supervisor_mode_kernel ) - { - v->arch.pv_vcpu.kernel_ss &= ~3; - v->arch.user_regs.ss &= ~3; - v->arch.user_regs.es &= ~3; - v->arch.user_regs.ds &= ~3; - v->arch.user_regs.fs &= ~3; - v->arch.user_regs.gs &= ~3; - printk("Dom0 runs in ring 0 (supervisor mode)\n"); - if ( !test_bit(XENFEAT_supervisor_mode_kernel, - parms.f_supported) ) - panic("Dom0 does not support supervisor-mode execution"); - } - else - { - if ( test_bit(XENFEAT_supervisor_mode_kernel, parms.f_required) ) - panic("Dom0 requires supervisor-mode execution"); - } + /* + * PVH Fixme: XENFEAT_supervisor_mode_kernel has been reused in PVH with a + * different meaning. + */ + if ( test_bit(XENFEAT_supervisor_mode_kernel, parms.f_required) ) + panic("Dom0 requires supervisor-mode execution"); rc = 0; diff --git a/xen/common/domctl.c b/xen/common/domctl.c index f15dcfe..edadf74 100644 --- a/xen/common/domctl.c +++ b/xen/common/domctl.c @@ -534,8 +534,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl) unsigned int domcr_flags; ret = -EINVAL; - if ( supervisor_mode_kernel || - (op->u.createdomain.flags & + if ( (op->u.createdomain.flags & ~(XEN_DOMCTL_CDF_hvm_guest | XEN_DOMCTL_CDF_pvh_guest | XEN_DOMCTL_CDF_hap diff --git a/xen/common/kernel.c b/xen/common/kernel.c index d23c422..0d9e519 100644 --- a/xen/common/kernel.c +++ b/xen/common/kernel.c @@ -308,8 +308,6 @@ DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg) fi.submap |= (1U << XENFEAT_writable_page_tables) | (1U << XENFEAT_auto_translated_physmap); - if ( supervisor_mode_kernel ) - fi.submap |= 1U << XENFEAT_supervisor_mode_kernel; if ( is_hardware_domain(current->domain) ) fi.submap |= 1U << XENFEAT_dom0; #ifdef CONFIG_X86 diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h index 264e2c1..9e165db 100644 --- a/xen/include/asm-arm/config.h +++ b/xen/include/asm-arm/config.h @@ -196,8 +196,6 @@ extern unsigned long xenheap_phys_end; extern unsigned long frametable_virt_end; #endif -#define supervisor_mode_kernel (0) - #define watchdog_disable() ((void)0) #define watchdog_enable() ((void)0) diff --git a/xen/include/asm-x86/config.h b/xen/include/asm-x86/config.h index 3802721..ad52d5b 100644 --- a/xen/include/asm-x86/config.h +++ b/xen/include/asm-x86/config.h @@ -70,12 +70,6 @@ /* Maximum we can support with current vLAPIC ID mapping. */ #define MAX_HVM_VCPUS 128 -#ifdef CONFIG_X86_SUPERVISOR_MODE_KERNEL -# define supervisor_mode_kernel (1) -#else -# define supervisor_mode_kernel (0) -#endif - /* Linkage for x86 */ #define __ALIGN .align 16,0x90 #define __ALIGN_STR ".align 16,0x90" diff --git a/xen/include/asm-x86/desc.h b/xen/include/asm-x86/desc.h index 225913a..20c47d2 100644 --- a/xen/include/asm-x86/desc.h +++ b/xen/include/asm-x86/desc.h @@ -47,17 +47,7 @@ (sel) = (((sel) & 3) >= _rpl) ? (sel) : (((sel) & ~3) | _rpl); \ }) -/* Stack selectors don't need fixing up if the kernel runs in ring 0. */ -#ifdef CONFIG_X86_SUPERVISOR_MODE_KERNEL -#define fixup_guest_stack_selector(d, ss) ((void)0) -#else #define fixup_guest_stack_selector(d, ss) __fixup_guest_selector(d, ss) -#endif - -/* - * Code selectors are always fixed up. It allows the Xen exit stub to detect - * return to guest context, even when the guest kernel runs in ring 0. - */ #define fixup_guest_code_selector(d, cs) __fixup_guest_selector(d, cs) /* -- 1.7.10.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel

©2013 Xen Project, A Linux Foundation Collaborative Project. All Rights Reserved.
Linux Foundation is a registered trademark of The Linux Foundation.
Xen Project is a trademark of The Linux Foundation.