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808b049 |
x86/HVM: properly bound x2APIC MSR range
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808b049 |
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808b049 |
While the write path change appears to be purely cosmetic (but still
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808b049 |
gets done here for consistency), the read side mistake permitted
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808b049 |
accesses beyond the virtual APIC page.
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808b049 |
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Note that while this isn't fully in line with the specification
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(digesting MSRs 0x800-0xBFF for the x2APIC), this is the minimal
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808b049 |
possible fix addressing the security issue and getting x2APIC related
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808b049 |
code into a consistent shape (elsewhere a 256 rather than 1024 wide
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808b049 |
window is being used too). This will be dealt with subsequently.
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808b049 |
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This is XSA-108.
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808b049 |
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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--- a/xen/arch/x86/hvm/hvm.c
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+++ b/xen/arch/x86/hvm/hvm.c
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@@ -4380,7 +4380,7 @@ int hvm_msr_read_intercept(unsigned int
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*msr_content = vcpu_vlapic(v)->hw.apic_base_msr;
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break;
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808b049 |
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- case MSR_IA32_APICBASE_MSR ... MSR_IA32_APICBASE_MSR + 0x3ff:
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+ case MSR_IA32_APICBASE_MSR ... MSR_IA32_APICBASE_MSR + 0xff:
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if ( hvm_x2apic_msr_read(v, msr, msr_content) )
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goto gp_fault;
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break;
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@@ -4506,7 +4506,7 @@ int hvm_msr_write_intercept(unsigned int
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808b049 |
vlapic_tdt_msr_set(vcpu_vlapic(v), msr_content);
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break;
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808b049 |
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- case MSR_IA32_APICBASE_MSR ... MSR_IA32_APICBASE_MSR + 0x3ff:
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+ case MSR_IA32_APICBASE_MSR ... MSR_IA32_APICBASE_MSR + 0xff:
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if ( hvm_x2apic_msr_write(v, msr, msr_content) )
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goto gp_fault;
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break;
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