Messages in this thread | | | Date | Thu, 22 Mar 2007 09:20:32 +0200 | From | Avi Kivity <> | Subject | Re: [PATCH] make KVM conform to sucky rdmsr interface |
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Rusty Russell wrote: > Grrr.... Andi refused to take my "rdmsr64" patch which moved to a > function-like interface for MSRs, dismissing it as pointless churn. > > paravirt_ops cleanups changed a macro to an inline and spotted this > kvm bug. > > Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> > > diff -r 47c6ee74a5c5 drivers/kvm/vmx.c > --- a/drivers/kvm/vmx.c Thu Mar 22 12:57:44 2007 +1100 > +++ b/drivers/kvm/vmx.c Thu Mar 22 13:38:24 2007 +1100 > @@ -1127,7 +1127,7 @@ static int vmx_vcpu_setup(struct kvm_vcp > u64 data; > int j = vcpu->nmsrs; > > - if (rdmsr_safe(index, &data_low, &data_high) < 0) > + if (rdmsr_safe(index, data_low, data_high) < 0) > continue; > if (wrmsr_safe(index, data_low, data_high) < 0) > continue; > > >
My rdmsr_safe (x86_64, i386 is similar/same) is
#define rdmsr_safe(msr,a,b) \ ({ int ret__; \ asm volatile ("1: rdmsr\n" \ "2:\n" \ ".section .fixup,\"ax\"\n" \ "3: movl %4,%0\n" \ " jmp 2b\n" \ ".previous\n" \ ".section __ex_table,\"a\"\n" \ " .align 8\n" \ " .quad 1b,3b\n" \ ".previous":"=&bDS" (ret__), "=a"(*(a)), "=d"(*(b))\ :"c"(msr), "i"(-EIO), "0"(0)); \ ret__; })
Which seems quite happy to accept pointers to the values. The one in asm/i386/paravirt.h has a similar calling convention.
-- Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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