From ec35a69c467026437519bafcf325a7362e422db9 Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Tue, 16 Nov 2010 12:09:59 -0500 Subject: xen: set IO permission early (before early_cpu_init()) This patch is based off "xen dom0: Set up basic IO permissions for dom0." by Juan Quintela . On AMD machines when we boot the kernel as Domain 0 we get this nasty: mapping kernel into physical memory Xen: setup ISA identity maps about to get started... (XEN) traps.c:475:d0 Unhandled general protection fault fault/trap [#13] on VCPU 0 [ec=0000] (XEN) domain_crash_sync called from entry.S (XEN) Domain 0 (vcpu#0) crashed on cpu#0: (XEN) ----[ Xen-4.1-101116 x86_64 debug=y Not tainted ]---- (XEN) CPU: 0 (XEN) RIP: e033:[] (XEN) RFLAGS: 0000000000000282 EM: 1 CONTEXT: pv guest (XEN) rax: 000000008000c068 rbx: ffffffff8186c680 rcx: 0000000000000068 (XEN) rdx: 0000000000000cf8 rsi: 000000000000c000 rdi: 0000000000000000 (XEN) rbp: ffffffff81801e98 rsp: ffffffff81801e50 r8: ffffffff81801eac (XEN) r9: ffffffff81801ea8 r10: ffffffff81801eb4 r11: 00000000ffffffff (XEN) r12: ffffffff8186c694 r13: ffffffff81801f90 r14: ffffffffffffffff (XEN) r15: 0000000000000000 cr0: 000000008005003b cr4: 00000000000006f0 (XEN) cr3: 0000000221803000 cr2: 0000000000000000 (XEN) ds: 0000 es: 0000 fs: 0000 gs: 0000 ss: e02b cs: e033 (XEN) Guest stack trace from rsp=ffffffff81801e50: RIP points to read_pci_config() function. The issue is that we don't set IO permissions for the Linux kernel early enough. The call sequence used to be: xen_start_kernel() x86_init.oem.arch_setup = xen_setup_arch; setup_arch: - early_cpu_init - early_init_amd - read_pci_config - x86_init.oem.arch_setup [ xen_arch_setup ] - set IO permissions. We need to set the IO permissions earlier on, which this patch does. Acked-by: Jeremy Fitzhardinge Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/xen/enlighten.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'arch/x86/xen/enlighten.c') diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index bd3554934613..7250bef7f49e 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1095,6 +1095,8 @@ static void __init xen_setup_stackprotector(void) /* First C function to be called on Xen boot */ asmlinkage void __init xen_start_kernel(void) { + struct physdev_set_iopl set_iopl; + int rc; pgd_t *pgd; if (!xen_start_info) @@ -1209,10 +1211,18 @@ asmlinkage void __init xen_start_kernel(void) #else pv_info.kernel_rpl = 0; #endif - /* set the limit of our address space */ xen_reserve_top(); + /* We used to do this in xen_arch_setup, but that is too late on AMD + * were early_cpu_init (run before ->arch_setup()) calls early_amd_init + * which pokes 0xcf8 port. + */ + set_iopl.iopl = 1; + rc = HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl); + if (rc != 0) + xen_raw_printk("physdev_op failed %d\n", rc); + #ifdef CONFIG_X86_32 /* set up basic CPUID stuff */ cpu_detect(&new_cpu_data); -- cgit v1.2.3