Re: [Qemu-devel] [PATCH 0/5] target-i386: kvm: Increase MSR entry array limits, check for array overrun

[Paolo Bonzini]

On 16/12/2015 20:06, Eduardo Habkost wrote:
> We are dangerously close to the array limits in kvm_put_msrs()
> and kvm_get_msrs(): with the default mcg_cap configuration, we
> can set up to 148 MSRs in kvm_put_msrs(), and if we allow mcg_cap
> to be changed, we can write up to 236 MSRs[1].
> 
> This series changes the code to allocate a buffer once per VCPU,
> increase buffer size to 4096 bytes (that can hold up to 255 MSR
> entries), and check array limits before appending new entries.

Thanks, it's a good improvement.

Reviewed-by: Paolo Bonzini <address@hidden>

> [1] I have checked the limits by copying and pasting the
>     kvm_put_msrs() code to a new file, replacing the "if" lines,
>     copying the macro definitions, and adding a helper macro to
>     keep track of the kvm_msr_entry_set() calls. The code can be
>     seen at:
>     https://gist.github.com/ehabkost/08d4177a33b8648a71ef
> 
> Eduardo Habkost (5):
>   target-i386: kvm: Allocate kvm_msrs struct once per VCPU
>   target-i386: kvm: Increase MSR_BUF_SIZE
>   target-i386: kvm: Simplify MSR array construction
>   target-i386: kvm: Simplify MSR setting functions
>   target-i386: kvm: Eliminate kvm_msr_entry_set()
> 
>  target-i386/cpu-qom.h |   4 +
>  target-i386/kvm.c     | 322 
> +++++++++++++++++++++++---------------------------
>  2 files changed, 149 insertions(+), 177 deletions(-)
>