From: Yu Zhang <yu.c.zhang@linux.intel.com>
To: Jan Beulich <JBeulich@suse.com>, Paul Durrant <paul.durrant@citrix.com>
Cc: Kevin Tian <kevin.tian@intel.com>,
George Dunlap <george.dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Tim Deegan <tim@xen.org>,
xen-devel@lists.xen.org, zhiyuan.lv@intel.com,
Jun Nakajima <jun.nakajima@intel.com>
Subject: Re: [PATCH v5 3/4] x86/ioreq server: Add HVMOP to map guest ram with p2m_ioreq_server to an ioreq server.
Date: Tue, 9 Aug 2016 15:39:38 +0800 [thread overview]
Message-ID: <57A988BA.5020104@linux.intel.com> (raw)
In-Reply-To: <57A8C4270200007800103E80@prv-mh.provo.novell.com>
On 8/8/2016 11:40 PM, Jan Beulich wrote:
>>>> On 12.07.16 at 11:02, <yu.c.zhang@linux.intel.com> wrote:
>> @@ -178,8 +179,34 @@ static int hvmemul_do_io(
>> break;
>> case X86EMUL_UNHANDLEABLE:
>> {
>> - struct hvm_ioreq_server *s =
>> - hvm_select_ioreq_server(curr->domain, &p);
>> + struct hvm_ioreq_server *s;
>> +
>> + if ( is_mmio )
>> + {
>> + unsigned long gmfn = paddr_to_pfn(addr);
>> + p2m_type_t p2mt;
>> +
>> + (void) get_gfn_query_unlocked(currd, gmfn, &p2mt);
>> +
>> + if ( p2mt == p2m_ioreq_server )
>> + {
>> + unsigned int flags;
>> +
>> + if ( dir != IOREQ_WRITE )
>> + s = NULL;
>> + else
>> + {
>> + s = p2m_get_ioreq_server(currd, &flags);
>> +
>> + if ( !(flags & P2M_IOREQ_HANDLE_WRITE_ACCESS) )
>> + s = NULL;
>> + }
>> + }
>> + else
>> + s = hvm_select_ioreq_server(currd, &p);
>> + }
>> + else
>> + s = hvm_select_ioreq_server(currd, &p);
> Wouldn't it both be more natural and make the logic even easier
> to follow if s got set to NULL up front, all the "else"-s dropped,
> and a simple
>
> if ( !s )
> s = hvm_select_ioreq_server(currd, &p);
>
> be done in the end?
Thanks, Jan. I'll have a try.
>> @@ -5447,6 +5452,21 @@ static int hvmop_set_mem_type(
>> if ( !is_hvm_domain(d) )
>> goto out;
>>
>> + if ( a.hvmmem_type == HVMMEM_ioreq_server )
>> + {
>> + unsigned int flags;
>> + struct hvm_ioreq_server *s;
>> +
>> + /* HVMMEM_ioreq_server is only supported for HAP enabled hvm. */
>> + if ( !hap_enabled(d) )
>> + goto out;
>> +
>> + /* Do not change to HVMMEM_ioreq_server if no ioreq server mapped. */
>> + s = p2m_get_ioreq_server(d, &flags);
>> + if ( s == NULL )
>> + goto out;
> Either drop s as an intermediate variable altogether (preferred), or
> constify it properly.
Got it.
>> +int hvm_map_mem_type_to_ioreq_server(struct domain *d, ioservid_t id,
>> + uint32_t type, uint32_t flags)
>> +{
>> + struct hvm_ioreq_server *s;
>> + int rc;
>> +
>> + /* For now, only HVMMEM_ioreq_server is supported. */
>> + if ( type != HVMMEM_ioreq_server )
>> + return -EINVAL;
>> +
>> + /* For now, only write emulation is supported. */
>> + if ( flags & ~(XEN_HVMOP_IOREQ_MEM_ACCESS_WRITE) )
>> + return -EINVAL;
>> +
>> + spin_lock(&d->arch.hvm_domain.ioreq_server.lock);
> This lock did get converted to a recursive one a little while back.
Oh. I see, should use the spin_lock_recursive/spin_unlock_recursive
pair. Thanks.
>> + rc = -ENOENT;
>> + list_for_each_entry ( s,
>> + &d->arch.hvm_domain.ioreq_server.list,
>> + list_entry )
>> + {
>> + if ( s == d->arch.hvm_domain.default_ioreq_server )
>> + continue;
>> +
>> + if ( s->id == id )
>> + {
>> + rc = p2m_set_ioreq_server(d, flags, s);
>> + if ( rc == 0 )
>> + dprintk(XENLOG_DEBUG, "%u %s type HVMMEM_ioreq_server.\n",
>> + s->id, (flags != 0) ? "mapped to" : "unmapped from");
> Is this really useful?
Sorry, are you referring to this debug message?
I believe it helps, especially when multiple ioreq servers are
claiming/disclaiming their ownership of
the HVMMEM_ioreq_server. :)
>> --- a/xen/arch/x86/mm/p2m-ept.c
>> +++ b/xen/arch/x86/mm/p2m-ept.c
>> @@ -132,6 +132,13 @@ static void ept_p2m_type_to_flags(struct p2m_domain *p2m, ept_entry_t *entry,
>> entry->r = entry->w = entry->x = 1;
>> entry->a = entry->d = !!cpu_has_vmx_ept_ad;
>> break;
>> + case p2m_ioreq_server:
>> + entry->r = 1;
>> + entry->w = !(p2m->ioreq.flags & P2M_IOREQ_HANDLE_WRITE_ACCESS);
>> + entry->x = 0;
>> + entry->a = !!cpu_has_vmx_ept_ad;
>> + entry->d = entry->w && cpu_has_vmx_ept_ad;
> For self-consistency, could this become
>
> entry->d = entry->w && entry->a;
>
> ?
Yep. Thanks. :)
>> --- a/xen/arch/x86/mm/shadow/multi.c
>> +++ b/xen/arch/x86/mm/shadow/multi.c
>> @@ -3225,8 +3225,7 @@ static int sh_page_fault(struct vcpu *v,
>> }
>>
>> /* Need to hand off device-model MMIO to the device model */
>> - if ( p2mt == p2m_mmio_dm
>> - || (p2mt == p2m_ioreq_server && ft == ft_demand_write) )
>> + if ( p2mt == p2m_mmio_dm )
> Could you remind me again what the code being removed here gets
> replaced by, or why it doesn't need any replacement?
HVMMEM_ioreq_server is now only supported for HAP enabled hvm, so
shadow code
does not need to handle this p2m type.
>> @@ -336,6 +336,23 @@ struct p2m_domain {
>> struct ept_data ept;
>> /* NPT-equivalent structure could be added here. */
>> };
>> +
>> + struct {
>> + spinlock_t lock;
>> + /*
>> + * ioreq server who's responsible for the emulation of
>> + * gfns with specific p2m type(for now, p2m_ioreq_server).
>> + */
>> + struct hvm_ioreq_server *server;
>> + /*
>> + * flags specifies whether read, write or both operations
>> + * are to be emulated by an ioreq server.
>> + */
>> + unsigned int flags;
>> +
>> +#define P2M_IOREQ_HANDLE_WRITE_ACCESS XEN_HVMOP_IOREQ_MEM_ACCESS_WRITE
>> +#define P2M_IOREQ_HANDLE_READ_ACCESS XEN_HVMOP_IOREQ_MEM_ACCESS_READ
> I think I did say so on a previous iteration already: I can't see the
> value of these two defines, or in fact I can see these being actively
> dangerous: The rest of your patch assume that each pair shares
> their values (as there's no translation between them, but also no
> BUILD_BUG_ON() ensuring they're identical).
Oh. I thought it was a coding style issue we were discussing -
previously, there was a
#define using the <underscore><uppercase> pattern, which should be
deprecated.
For the P2M_IOREQ_HANDLE_WRITE/READ_ACCESS definition, I agree they can
be removed.
>
>> --- a/xen/include/public/hvm/hvm_op.h
>> +++ b/xen/include/public/hvm/hvm_op.h
>> @@ -89,7 +89,9 @@ typedef enum {
>> HVMMEM_unused, /* Placeholder; setting memory to this type
>> will fail for code after 4.7.0 */
>> #endif
>> - HVMMEM_ioreq_server
>> + HVMMEM_ioreq_server /* Memory type claimed by an ioreq server; type
>> + changes to this value are only allowed after
>> + an ioreq server has claimed its ownership. */
> Wouldn't it be worth also noting in the comment that only changes
> to/from rw are permitted?
>
OK. Will add this comment in next version.
Yu
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next prev parent reply other threads:[~2016-08-09 7:39 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-12 9:02 [PATCH v5 0/4] x86/ioreq server: Introduce HVMMEM_ioreq_server mem type Yu Zhang
2016-07-12 9:02 ` [PATCH v5 1/4] x86/ioreq server: Rename p2m_mmio_write_dm to p2m_ioreq_server Yu Zhang
2016-07-12 9:02 ` [PATCH v5 2/4] x86/ioreq server: Add new functions to get/set memory types Yu Zhang
2016-07-12 9:02 ` [PATCH v5 3/4] x86/ioreq server: Add HVMOP to map guest ram with p2m_ioreq_server to an ioreq server Yu Zhang
2016-08-08 15:40 ` Jan Beulich
2016-08-09 7:39 ` Yu Zhang [this message]
2016-08-09 8:11 ` Jan Beulich
2016-08-09 8:20 ` Paul Durrant
2016-08-09 8:51 ` Yu Zhang
2016-08-09 9:07 ` Paul Durrant
2016-08-10 8:09 ` Yu Zhang
2016-08-10 10:33 ` Jan Beulich
2016-08-10 10:43 ` Paul Durrant
2016-08-10 12:32 ` Yu Zhang
2016-08-10 10:43 ` Yu Zhang
2016-08-11 8:47 ` Yu Zhang
2016-08-11 8:58 ` Jan Beulich
2016-08-11 9:19 ` Yu Zhang
2016-07-12 9:02 ` [PATCH v5 4/4] x86/ioreq server: Reset outstanding p2m_ioreq_server entries when an ioreq server unmaps Yu Zhang
2016-08-08 16:29 ` Jan Beulich
2016-08-09 7:39 ` Yu Zhang
2016-08-09 8:13 ` Jan Beulich
2016-08-09 9:25 ` Yu Zhang
2016-08-09 9:45 ` Jan Beulich
2016-08-09 10:21 ` Yu Zhang
2016-08-16 13:35 ` George Dunlap
2016-08-16 13:54 ` Jan Beulich
2016-08-30 12:17 ` Yu Zhang
2016-09-02 11:00 ` Yu Zhang
2016-08-05 2:44 ` [PATCH v5 0/4] x86/ioreq server: Introduce HVMMEM_ioreq_server mem type Yu Zhang
2016-08-05 6:16 ` Jan Beulich
2016-08-05 12:46 ` George Dunlap
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