linux/arch/x86/xen/xen-head.S
Juergen Gross 8f5b0c6398 xen: eliminate scalability issues from initial mapping setup
Direct Xen to place the initial P->M table outside of the initial
mapping, as otherwise the 1G (implementation) / 2G (theoretical)
restriction on the size of the initial mapping limits the amount
of memory a domain can be handed initially.

As the initial P->M table is copied rather early during boot to
domain private memory and it's initial virtual mapping is dropped,
the easiest way to avoid virtual address conflicts with other
addresses in the kernel is to use a user address area for the
virtual address of the initial P->M table. This allows us to just
throw away the page tables of the initial mapping after the copy
without having to care about address invalidation.

It should be noted that this patch won't enable a pv-domain to USE
more than 512 GB of RAM. It just enables it to be started with a
P->M table covering more memory. This is especially important for
being able to boot a Dom0 on a system with more than 512 GB memory.

Signed-off-by: Juergen Gross <jgross@suse.com>
Based-on-patch-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
2015-08-20 12:24:18 +01:00

125 lines
3.8 KiB
ArmAsm

/* Xen-specific pieces of head.S, intended to be included in the right
place in head.S */
#ifdef CONFIG_XEN
#include <linux/elfnote.h>
#include <linux/init.h>
#include <asm/boot.h>
#include <asm/asm.h>
#include <asm/page_types.h>
#include <xen/interface/elfnote.h>
#include <xen/interface/features.h>
#include <xen/interface/xen.h>
#include <xen/interface/xen-mca.h>
#include <asm/xen/interface.h>
#ifdef CONFIG_XEN_PVH
#define PVH_FEATURES_STR "|writable_descriptor_tables|auto_translated_physmap|supervisor_mode_kernel"
/* Note the lack of 'hvm_callback_vector'. Older hypervisor will
* balk at this being part of XEN_ELFNOTE_FEATURES, so we put it in
* XEN_ELFNOTE_SUPPORTED_FEATURES which older hypervisors will ignore.
*/
#define PVH_FEATURES ((1 << XENFEAT_writable_page_tables) | \
(1 << XENFEAT_auto_translated_physmap) | \
(1 << XENFEAT_supervisor_mode_kernel) | \
(1 << XENFEAT_hvm_callback_vector))
/* The XENFEAT_writable_page_tables is not stricly neccessary as we set that
* up regardless whether this CONFIG option is enabled or not, but it
* clarifies what the right flags need to be.
*/
#else
#define PVH_FEATURES_STR ""
#define PVH_FEATURES (0)
#endif
__INIT
ENTRY(startup_xen)
cld
#ifdef CONFIG_X86_32
mov %esi,xen_start_info
mov $init_thread_union+THREAD_SIZE,%esp
#else
mov %rsi,xen_start_info
mov $init_thread_union+THREAD_SIZE,%rsp
#endif
jmp xen_start_kernel
__FINIT
#ifdef CONFIG_XEN_PVH
/*
* xen_pvh_early_cpu_init() - early PVH VCPU initialization
* @cpu: this cpu number (%rdi)
* @entry: true if this is a secondary vcpu coming up on this entry
* point, false if this is the boot CPU being initialized for
* the first time (%rsi)
*
* Note: This is called as a function on the boot CPU, and is the entry point
* on the secondary CPU.
*/
ENTRY(xen_pvh_early_cpu_init)
mov %rsi, %r11
/* Gather features to see if NX implemented. */
mov $0x80000001, %eax
cpuid
mov %edx, %esi
mov $MSR_EFER, %ecx
rdmsr
bts $_EFER_SCE, %eax
bt $20, %esi
jnc 1f /* No NX, skip setting it */
bts $_EFER_NX, %eax
1: wrmsr
#ifdef CONFIG_SMP
cmp $0, %r11b
jne cpu_bringup_and_idle
#endif
ret
#endif /* CONFIG_XEN_PVH */
.pushsection .text
.balign PAGE_SIZE
ENTRY(hypercall_page)
.skip PAGE_SIZE
#define HYPERCALL(n) \
.equ xen_hypercall_##n, hypercall_page + __HYPERVISOR_##n * 32; \
.type xen_hypercall_##n, @function; .size xen_hypercall_##n, 32
#include <asm/xen-hypercalls.h>
#undef HYPERCALL
.popsection
ELFNOTE(Xen, XEN_ELFNOTE_GUEST_OS, .asciz "linux")
ELFNOTE(Xen, XEN_ELFNOTE_GUEST_VERSION, .asciz "2.6")
ELFNOTE(Xen, XEN_ELFNOTE_XEN_VERSION, .asciz "xen-3.0")
#ifdef CONFIG_X86_32
ELFNOTE(Xen, XEN_ELFNOTE_VIRT_BASE, _ASM_PTR __PAGE_OFFSET)
#else
ELFNOTE(Xen, XEN_ELFNOTE_VIRT_BASE, _ASM_PTR __START_KERNEL_map)
/* Map the p2m table to a 512GB-aligned user address. */
ELFNOTE(Xen, XEN_ELFNOTE_INIT_P2M, .quad PGDIR_SIZE)
#endif
ELFNOTE(Xen, XEN_ELFNOTE_ENTRY, _ASM_PTR startup_xen)
ELFNOTE(Xen, XEN_ELFNOTE_HYPERCALL_PAGE, _ASM_PTR hypercall_page)
ELFNOTE(Xen, XEN_ELFNOTE_FEATURES, .ascii "!writable_page_tables|pae_pgdir_above_4gb"; .asciz PVH_FEATURES_STR)
ELFNOTE(Xen, XEN_ELFNOTE_SUPPORTED_FEATURES, .long (PVH_FEATURES) |
(1 << XENFEAT_writable_page_tables) |
(1 << XENFEAT_dom0))
ELFNOTE(Xen, XEN_ELFNOTE_PAE_MODE, .asciz "yes")
ELFNOTE(Xen, XEN_ELFNOTE_LOADER, .asciz "generic")
ELFNOTE(Xen, XEN_ELFNOTE_L1_MFN_VALID,
.quad _PAGE_PRESENT; .quad _PAGE_PRESENT)
ELFNOTE(Xen, XEN_ELFNOTE_SUSPEND_CANCEL, .long 1)
ELFNOTE(Xen, XEN_ELFNOTE_MOD_START_PFN, .long 1)
ELFNOTE(Xen, XEN_ELFNOTE_HV_START_LOW, _ASM_PTR __HYPERVISOR_VIRT_START)
ELFNOTE(Xen, XEN_ELFNOTE_PADDR_OFFSET, _ASM_PTR 0)
#endif /*CONFIG_XEN */