From: "Jan Beulich" <JBeulich@suse.com>
To: Paul Durrant <paul.durrant@citrix.com>,
Yu Zhang <yu.c.zhang@linux.intel.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: Mon, 08 Aug 2016 09:40:55 -0600 [thread overview]
Message-ID: <57A8C4270200007800103E80@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1468314129-28465-4-git-send-email-yu.c.zhang@linux.intel.com>
>>> 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?
> @@ -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.
> +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.
> + 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?
> --- 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;
?
> --- 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?
> @@ -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).
> --- 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?
Jan
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next prev parent reply other threads:[~2016-08-08 15:40 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 [this message]
2016-08-09 7:39 ` Yu Zhang
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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