Vitaly Kuznetsov b062b794c7 x86/kvm/vmx: don't read current->thread.{fs,gs}base of legacy tasks ... When we switched from doing rdmsr() to reading FS/GS base values from current->thread we completely forgot about legacy 32-bit userspaces which we still support in KVM (why?). task->thread.{fsbase,gsbase} are only synced for 64-bit processes, calling save_fsgs_for_kvm() and using its result from current is illegal for legacy processes. There's no ARCH_SET_FS/GS prctls for legacy applications. Base MSRs are, however, not always equal to zero. Intel's manual says (3.4.4 Segment Loading Instructions in IA-32e Mode): "In order to set up compatibility mode for an application, segment-load instructions (MOV to Sreg, POP Sreg) work normally in 64-bit mode. An entry is read from the system descriptor table (GDT or LDT) and is loaded in the hidden portion of the segment register. ... The hidden descriptor register fields for FS.base and GS.base are physically mapped to MSRs in order to load all address bits supported by a 64-bit implementation. " The issue was found by strace test suite where 32-bit ioctl_kvm_run test started segfaulting. Reported-by: Dmitry V. Levin <ldv@altlinux.org> Bisected-by: Masatake YAMATO <yamato@redhat.com> Fixes: 42b933b597 ("x86/kvm/vmx: read MSR_{FS,KERNEL_GS}_BASE from current->thread") Cc: stable@vger.kernel.org Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>		2018-07-15 16:27:21 +02:00
..
boot	Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-05-20 11:28:32 -07:00
configs
crypto
entry	x86/vdso: Remove unused file	2018-05-05 09:02:36 +02:00
events	perf/x86/cstate: Fix possible Spectre-v1 indexing for pkg_msr	2018-05-05 08:37:31 +02:00
hyperv
ia32
include	Merge branch 'speck-v20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-05-21 11:23:26 -07:00
kernel	x86/speculation: Simplify the CPU bug detection logic	2018-05-23 10:55:52 +02:00
kvm	x86/kvm/vmx: don't read current->thread.{fs,gs}base of legacy tasks	2018-07-15 16:27:21 +02:00
lib
math-emu
mm	x86/pkeys: Override pkey when moving away from PROT_EXEC	2018-05-14 11:14:45 +02:00
net	bpf, x64: fix memleak when not converging on calls	2018-05-02 12:35:47 -07:00
oprofile
pci
platform
power	x86/power/64: Fix page-table setup for temporary text mapping	2018-04-20 11:52:00 +02:00
purgatory	kernel/kexec_file.c: move purgatories sha256 to common code	2018-04-13 17:10:28 -07:00
ras
realmode
tools
um
video
xen	Some of the ftrace internal events use a zero for a data size of	2018-05-16 16:45:23 -07:00
.gitignore
Kbuild
Kconfig	x86/pti: Filter at vma->vm_page_prot population	2018-04-25 11:02:51 +02:00
Kconfig.cpu
Kconfig.debug
Makefile
Makefile_32.cpu
Makefile.um