Re: [PATCH v2 0/4] Remove 32-bit Xen PV guest support
On 02.07.20 16:48, Brian Gerst wrote: On Wed, Jul 1, 2020 at 7:07 AM Juergen Gross wrote: The long term plan has been to replace Xen PV guests by PVH. The first victim of that plan are now 32-bit PV guests, as those are used only rather seldom these days. Xen on x86 requires 64-bit support and with Grub2 now supporting PVH officially since version 2.04 there is no need to keep 32-bit PV guest support alive in the Linux kernel. Additionally Meltdown mitigation is not available in the kernel running as 32-bit PV guest, so dropping this mode makes sense from security point of view, too. One thing that you missed is removing VDSO_NOTE_NONEGSEG_BIT from vdso32/note.S. With that removed there is no difference from the 64-bit version. Oh, this means we can probably remove arch/x86/xen/vdso.h completely. Otherwise this series looks good to me. Thanks, Juergen
Re: [PATCH v2 0/4] Remove 32-bit Xen PV guest support
On Wed, Jul 1, 2020 at 7:07 AM Juergen Gross wrote: > > The long term plan has been to replace Xen PV guests by PVH. The first > victim of that plan are now 32-bit PV guests, as those are used only > rather seldom these days. Xen on x86 requires 64-bit support and with > Grub2 now supporting PVH officially since version 2.04 there is no > need to keep 32-bit PV guest support alive in the Linux kernel. > Additionally Meltdown mitigation is not available in the kernel running > as 32-bit PV guest, so dropping this mode makes sense from security > point of view, too. One thing that you missed is removing VDSO_NOTE_NONEGSEG_BIT from vdso32/note.S. With that removed there is no difference from the 64-bit version. Otherwise this series looks good to me. -- Brian Gerst
Re: [PATCH v2 0/4] Remove 32-bit Xen PV guest support
On Wed, Jul 01, 2020 at 01:06:46PM +0200, Juergen Gross wrote: > The long term plan has been to replace Xen PV guests by PVH. The first > victim of that plan are now 32-bit PV guests, as those are used only > rather seldom these days. Xen on x86 requires 64-bit support and with > Grub2 now supporting PVH officially since version 2.04 there is no > need to keep 32-bit PV guest support alive in the Linux kernel. > Additionally Meltdown mitigation is not available in the kernel running > as 32-bit PV guest, so dropping this mode makes sense from security > point of view, too. Hooray!!! Much thanks!
[PATCH v2 0/4] Remove 32-bit Xen PV guest support
The long term plan has been to replace Xen PV guests by PVH. The first victim of that plan are now 32-bit PV guests, as those are used only rather seldom these days. Xen on x86 requires 64-bit support and with Grub2 now supporting PVH officially since version 2.04 there is no need to keep 32-bit PV guest support alive in the Linux kernel. Additionally Meltdown mitigation is not available in the kernel running as 32-bit PV guest, so dropping this mode makes sense from security point of view, too. Changes in V2: - rebase to 5.8 kernel - addressed comments to V1 - new patches 3 and 4 Juergen Gross (4): x86/xen: remove 32-bit Xen PV guest support x86/paravirt: remove 32-bit support from PARAVIRT_XXL x86/paravirt: cleanup paravirt macros x86/paravirt: use CONFIG_PARAVIRT_XXL instead of CONFIG_PARAVIRT arch/x86/entry/entry_32.S | 109 +-- arch/x86/entry/entry_64.S | 4 +- arch/x86/entry/vdso/vdso32/vclock_gettime.c | 1 + arch/x86/include/asm/fixmap.h | 2 +- arch/x86/include/asm/paravirt.h | 107 +- arch/x86/include/asm/paravirt_types.h | 21 -- arch/x86/include/asm/pgtable-3level_types.h | 5 - arch/x86/include/asm/proto.h| 2 +- arch/x86/include/asm/required-features.h| 2 +- arch/x86/include/asm/segment.h | 6 +- arch/x86/kernel/cpu/common.c| 8 - arch/x86/kernel/head_32.S | 31 -- arch/x86/kernel/kprobes/core.c | 1 - arch/x86/kernel/kprobes/opt.c | 1 - arch/x86/kernel/paravirt.c | 18 -- arch/x86/kernel/paravirt_patch.c| 17 - arch/x86/xen/Kconfig| 3 +- arch/x86/xen/Makefile | 3 +- arch/x86/xen/apic.c | 17 - arch/x86/xen/enlighten_pv.c | 52 +-- arch/x86/xen/mmu_pv.c | 340 +++- arch/x86/xen/p2m.c | 6 +- arch/x86/xen/setup.c| 35 +- arch/x86/xen/smp_pv.c | 18 -- arch/x86/xen/xen-asm.S | 182 ++- arch/x86/xen/xen-asm_32.S | 185 --- arch/x86/xen/xen-asm_64.S | 181 --- arch/x86/xen/xen-head.S | 6 - drivers/xen/Kconfig | 4 +- 29 files changed, 232 insertions(+), 1135 deletions(-) delete mode 100644 arch/x86/xen/xen-asm_32.S delete mode 100644 arch/x86/xen/xen-asm_64.S -- 2.26.2
