[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [v3][PATCH 02/16] xen/x86/p2m: introduce set_identity_p2m_entry
On 2015/6/11 15:33, Jan Beulich wrote: On 11.06.15 at 03:15, <tiejun.chen@xxxxxxxxx> wrote:We will create this sort of identity mapping as follows: If the gfn space is unoccupied, we just set the mapping. If the space is already occupied by 1:1 mappings, do nothing. Failed for any other cases. Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>First of all you continue to be copying each patch to every maintainer involved in some part of the series. Please limit the I just hope all involved guys can see this series on the whole to review. But, Cc list of each patch to the actual list of people needing to be Cc-ed on it (or you know explicitly wanting a copy). Next, I will just send them to each associated maintainer. --- a/xen/arch/x86/mm/p2m.c +++ b/xen/arch/x86/mm/p2m.c @@ -898,6 +898,41 @@ int set_mmio_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn, return set_typed_p2m_entry(d, gfn, mfn, p2m_mmio_direct, access); } +int set_identity_p2m_entry(struct domain *d, unsigned long gfn, + p2m_access_t p2ma) +{ + p2m_type_t p2mt; + p2m_access_t a; + mfn_t mfn; + struct p2m_domain *p2m = p2m_get_hostp2m(d); + int ret; + + if ( paging_mode_translate(p2m->domain) ) + { + gfn_lock(p2m, gfn, 0); + + mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL); + + if ( p2mt == p2m_invalid || mfn_x(mfn) == INVALID_MFN )I'm not fundamentally opposed to this extra INVALID_MFN check, but could you please clarify for which P2M type you saw INVALID_MFN coming back here, and for which p2m_invalid cases you didn't also see INVALID_MFN? I.e. I'd really prefer a single check to be used when that can cover all cases. Actually, I initially adopted "!mfn_valid(mfn)" in our previous version. But Tim issued one comment about this, "I don't think this check is quite right -- for example, this p2m entry might be an MMIO mapping or a PoD entry. "if ( p2mt == p2m_invalid )" would be better."But if I just keep his recommended check, you can see the following when I pass through IGD, (XEN) Cannot identity map d1:ad800, already mapped to ffffffffffffffff with p2mt:4. Looks "4" indicates p2m_mmio_dm, right? + ret = p2m_set_entry(p2m, gfn, _mfn(gfn), PAGE_ORDER_4K, + p2m_mmio_direct, p2ma); + else if ( mfn_x(mfn) == gfn && p2mt == p2m_mmio_direct && a == p2ma ) + ret = 0; + else + { + ret = -EBUSY; + printk(XENLOG_G_WARNING + "Cannot identity map d%d:%lx, already mapped to %lx.\n", + d->domain_id, gfn, mfn_x(mfn)); + } + + gfn_unlock(p2m, gfn, 0); + return ret; + } + + return 0; +}Either have a single return point, or invert the original if() and bail early (reducing the indentation level on the main body of the code). Sure, I guess I can follow this patten, int ret = 0; if () { ... } return ret; Thanks Tiejun Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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