diff options
| author | Jeremy Fitzhardinge | 2008-07-08 15:07:16 -0700 |
|---|---|---|
| committer | Ingo Molnar | 2008-07-16 11:06:20 +0200 |
| commit | 1153968a48e3ca3e2b7a437e8b82ec9e6f768e24 (patch) | |
| tree | 1dd347e5ae7a472f2757915d5927eaca4404d15a /arch/x86/xen | |
| parent | bf18bf94dc72db998d0fbebc846c07c858a59c90 (diff) | |
xen: implement Xen write_msr operation
64-bit uses MSRs for important things like the base for fs and
gs-prefixed addresses. It's more efficient to use a hypercall to
update these, rather than go via the trap and emulate path.
Other MSR writes are just passed through; in an unprivileged domain
they do nothing, but it might be useful later.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/xen')
| -rw-r--r-- | arch/x86/xen/enlighten.c | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index f64b8729cd07..776c0fb77d69 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -41,6 +41,7 @@ #include <asm/xen/hypervisor.h> #include <asm/fixmap.h> #include <asm/processor.h> +#include <asm/msr-index.h> #include <asm/setup.h> #include <asm/desc.h> #include <asm/pgtable.h> @@ -777,6 +778,34 @@ static void xen_write_cr3(unsigned long cr3) xen_mc_issue(PARAVIRT_LAZY_CPU); /* interrupts restored */ } +static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high) +{ + int ret; + + ret = 0; + + switch(msr) { +#ifdef CONFIG_X86_64 + unsigned which; + u64 base; + + case MSR_FS_BASE: which = SEGBASE_FS; goto set; + case MSR_KERNEL_GS_BASE: which = SEGBASE_GS_USER; goto set; + case MSR_GS_BASE: which = SEGBASE_GS_KERNEL; goto set; + + set: + base = ((u64)high << 32) | low; + if (HYPERVISOR_set_segment_base(which, base) != 0) + ret = -EFAULT; + break; +#endif + default: + ret = native_write_msr_safe(msr, low, high); + } + + return ret; +} + /* Early in boot, while setting up the initial pagetable, assume everything is pinned. */ static __init void xen_alloc_pte_init(struct mm_struct *mm, u32 pfn) @@ -1165,7 +1194,7 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = { .wbinvd = native_wbinvd, .read_msr = native_read_msr_safe, - .write_msr = native_write_msr_safe, + .write_msr = xen_write_msr_safe, .read_tsc = native_read_tsc, .read_pmc = native_read_pmc, |