Date: Thu, 29 Oct 2015 13:53:25 -0500 From: Alan Cox <alc@rice.edu> To: John Baldwin <jhb@freebsd.org>, Steven Wahl <Steve_Wahl@dell.com> Cc: "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "kib@freebsd.org" <kib@freebsd.org>, "cem@freebsd.org" <cem@freebsd.org>, Eric Van Gyzen <Eric.VanGyzen@compellent.com>, "?Alan L. Cox" <alc@freebsd.org> Subject: Re: svn commit: r290130 - head/sys/dev/ntb/ntb_hw Message-ID: <56326B25.8000102@rice.edu> In-Reply-To: <1968754.iCngWsIWpR@ralph.baldwin.cx> References: <bbf3208d2a4d40998c2154402208c016@mspexmb1.Beer.Town> <1968754.iCngWsIWpR@ralph.baldwin.cx>
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On 10/29/2015 12:02, John Baldwin wrote:
> On Thursday, October 29, 2015 04:42:20 PM Steven Wahl wrote:
>> We ran into this exact problem, pmap_change_attr not working right with large bars. I had been working up to seeing if this compiles on the current head, introducing myself to the community, seeing if this would be accepted.
>>
>> But looks like it's needed sooner, so in case it might save you some time, here's the patch we developed for this problem.
>>
>> --> Steve Wahl, Dell Compellent, Eden Prairie, MN
> Adding alc@, but on first blush this looks correct to me.
I agree. Commit it.
>> commit 7d112aa8767390cb9dd020325a9f23aaac7fe5a0
>> Author: swahl <steve_wahl@dell.com>
>> Date: Thu Oct 1 14:36:48 2015 -0500
>>
>> CQ00492954: FreeBSD traps on call to pmap_change_attr() with large PLX BAR
>>
>> If an address passed to pmap_change_attr() refers to a virtual address,
>> the function must also change the direct mapping of this same
>> region (if any) to match, or intel says the result is undefined.
>>
>> But the original code did not check if the virtual address actually fell
>> within the direct mapped region before attempting to make this change.
>> The attempt to look up the direct mapped page entries returned NULL, and
>> this was dereferenced causing a panic.
>>
>> This is fixed by checking whether the address is outside of the direct
>> mapped range before trying to change the direct mapped entries.
>>
>> diff --git a/src/sys/amd64/amd64/pmap.c b/src/sys/amd64/amd64/pmap.c
>> index fe09ace..dee22de 100644
>> --- a/src/sys/amd64/amd64/pmap.c
>> +++ b/src/sys/amd64/amd64/pmap.c
>> @@ -6268,7 +6268,7 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
>> */
>> for (tmpva = base; tmpva < base + size; ) {
>> pdpe = pmap_pdpe(kernel_pmap, tmpva);
>> - if (*pdpe == 0)
>> + if (pdpe == NULL || *pdpe == 0)
>> return (EINVAL);
>> if (*pdpe & PG_PS) {
>> /*
>> @@ -6341,7 +6341,8 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
>> X86_PG_PDE_CACHE);
>> changed = TRUE;
>> }
>> - if (tmpva >= VM_MIN_KERNEL_ADDRESS) {
>> + if (tmpva >= VM_MIN_KERNEL_ADDRESS &&
>> + (*pdpe & PG_PS_FRAME) < dmaplimit) {
>> if (pa_start == pa_end) {
>> /* Start physical address run. */
>> pa_start = *pdpe & PG_PS_FRAME;
>> @@ -6370,7 +6371,8 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
>> X86_PG_PDE_CACHE);
>> changed = TRUE;
>> }
>> - if (tmpva >= VM_MIN_KERNEL_ADDRESS) {
>> + if (tmpva >= VM_MIN_KERNEL_ADDRESS &&
>> + (*pde & PG_PS_FRAME) < dmaplimit) {
>> if (pa_start == pa_end) {
>> /* Start physical address run. */
>> pa_start = *pde & PG_PS_FRAME;
>> @@ -6397,7 +6399,8 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
>> X86_PG_PTE_CACHE);
>> changed = TRUE;
>> }
>> - if (tmpva >= VM_MIN_KERNEL_ADDRESS) {
>> + if (tmpva >= VM_MIN_KERNEL_ADDRESS &&
>> + (*pte & PG_FRAME) < dmaplimit) {
>> if (pa_start == pa_end) {
>> /* Start physical address run. */
>> pa_start = *pte & PG_FRAME;
>>
>
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