From 2b7cc93682acf720f6b2e1a690ccdae71129e6fc Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Wed, 24 Jan 2018 14:23:31 +0100 Subject: [PATCH] x86/hyperv: Check for required priviliges in hyperv_init() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit [ Upstream commit 89a8f6d4904c8cf3ff8fee9fdaff392a6bbb8bf6 ] In hyperv_init() its presumed that it always has access to VP index and hypercall MSRs while according to the specification it should be checked if it's allowed to access the corresponding MSRs before accessing them. Signed-off-by: Vitaly Kuznetsov Signed-off-by: Thomas Gleixner Reviewed-by: Thomas Gleixner Cc: Stephen Hemminger Cc: kvm@vger.kernel.org Cc: Radim Krčmář Cc: Haiyang Zhang Cc: "Michael Kelley (EOSG)" Cc: Roman Kagan Cc: Andy Lutomirski Cc: devel@linuxdriverproject.org Cc: Paolo Bonzini Cc: "K. Y. Srinivasan" Cc: Cathy Avery Cc: Mohammed Gamal Link: https://lkml.kernel.org/r/20180124132337.30138-2-vkuznets@redhat.com Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/x86/hyperv/hv_init.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index a0b86cf486e0..2e9d58cc371e 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -110,12 +110,19 @@ static int hv_cpu_init(unsigned int cpu) */ void hyperv_init(void) { - u64 guest_id; + u64 guest_id, required_msrs; union hv_x64_msr_hypercall_contents hypercall_msr; if (x86_hyper_type != X86_HYPER_MS_HYPERV) return; + /* Absolutely required MSRs */ + required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE | + HV_X64_MSR_VP_INDEX_AVAILABLE; + + if ((ms_hyperv.features & required_msrs) != required_msrs) + return; + /* Allocate percpu VP index */ hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index), GFP_KERNEL); -- 2.20.1