[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [Patch v2] x86/traps: improvements to {rd, wr}msr_hypervisor_regs()
Coverity ID: 1055249 1055250 Coverity was complaining that the switch statments contained dead code in their default statements. While this is quite minor, the code flow in wrmsr_hypervisor_regs() was sufficiently opaque that I felt it approprate to fix. Other improvements include: * not shadowing the function parameter 'idx'. * use of PAGE_SHIFT instead of opencoded numbers. * a more descriptive error message for attempting to write invalid indicies for hypercall pages. There is no behavioural change as a result. Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> CC: Keir Fraser <keir@xxxxxxx> CC: Jan Beulich <JBeulich@xxxxxxxx> --- xen/arch/x86/traps.c | 44 ++++++++++++++++++-------------------------- 1 file changed, 18 insertions(+), 26 deletions(-) diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c index 6c7bd99..8797e56 100644 --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -595,55 +595,50 @@ DO_ERROR_NOCODE(TRAP_copro_error, coprocessor_error) DO_ERROR( TRAP_alignment_check, alignment_check) DO_ERROR_NOCODE(TRAP_simd_error, simd_coprocessor_error) +/* + * Returns 0 if not handled, and non-0 for error. (The calling semantics are + * in need of some work) + */ int rdmsr_hypervisor_regs(uint32_t idx, uint64_t *val) { struct domain *d = current->domain; /* Optionally shift out of the way of Viridian architectural MSRs. */ uint32_t base = is_viridian_domain(d) ? 0x40000200 : 0x40000000; - idx -= base; - if ( idx > 0 ) - return 0; - - switch ( idx ) + switch ( idx - base ) { - case 0: + case 0: /* Write hypercall page. Reads are invalid. Hand a #GP back. */ { *val = 0; - break; + return 1; } - default: - BUG(); } - return 1; + return 0; } +/* Returns 1 if handled, 0 if not and -Exx for error. */ int wrmsr_hypervisor_regs(uint32_t idx, uint64_t val) { struct domain *d = current->domain; /* Optionally shift out of the way of Viridian architectural MSRs. */ uint32_t base = is_viridian_domain(d) ? 0x40000200 : 0x40000000; - idx -= base; - if ( idx > 0 ) - return 0; - - switch ( idx ) + switch ( idx - base ) { - case 0: + case 0: /* Write hypercall page */ { void *hypercall_page; - unsigned long gmfn = val >> 12; - unsigned int idx = val & 0xfff; + unsigned long gmfn = val >> PAGE_SHIFT; struct page_info *page; p2m_type_t t; - if ( idx > 0 ) + if ( val & 0xfff ) { + /* Bottom 12 bits are hypercall page index. Only 0 is valid. */ gdprintk(XENLOG_WARNING, - "Out of range index %u to MSR %08x\n", - idx, 0x40000000); + "wrmsr hypercall page index %#x unsupported\n", + val & 0xfff); return 0; } @@ -671,14 +666,11 @@ int wrmsr_hypervisor_regs(uint32_t idx, uint64_t val) unmap_domain_page(hypercall_page); put_page_and_type(page); - break; + return 1; } - - default: - BUG(); } - return 1; + return 0; } int cpuid_hypervisor_leaves( uint32_t idx, uint32_t sub_idx, -- 1.7.10.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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