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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC PATCH 1/5] ioreq-server: centralize access to ioreq structures
On 30/01/14 14:19, Paul Durrant wrote:
> To simplify creation of the ioreq server abstraction in a
> subsequent patch, this patch centralizes all use of the shared
> ioreq structure and the buffered ioreq ring to the source module
> xen/arch/x86/hvm/hvm.c.
> Also, re-work hvm_send_assist_req() slightly to complete IO
> immediately in the case where there is no emulator (i.e. the shared
> IOREQ ring has not been set). This should handle the case currently
> covered by has_dm in hvmemul_do_io().
>
> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> ---
> xen/arch/x86/hvm/emulate.c | 40 +++------------
> xen/arch/x86/hvm/hvm.c | 98
> ++++++++++++++++++++++++++++++++++++-
> xen/arch/x86/hvm/io.c | 94 +----------------------------------
> xen/include/asm-x86/hvm/hvm.h | 3 +-
> xen/include/asm-x86/hvm/support.h | 9 ----
> 5 files changed, 108 insertions(+), 136 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
> index 868aa1d..d1d3a6f 100644
> --- a/xen/arch/x86/hvm/emulate.c
> +++ b/xen/arch/x86/hvm/emulate.c
> @@ -57,24 +57,11 @@ static int hvmemul_do_io(
> int value_is_ptr = (p_data == NULL);
> struct vcpu *curr = current;
> struct hvm_vcpu_io *vio;
> - ioreq_t *p = get_ioreq(curr);
> - ioreq_t _ioreq;
> + ioreq_t p[1];
I know it will make the patch sightly larger by modifying the
indirection of p, but having an array of 1 item on the stack is seems silly.
> unsigned long ram_gfn = paddr_to_pfn(ram_gpa);
> p2m_type_t p2mt;
> struct page_info *ram_page;
> int rc;
> - bool_t has_dm = 1;
> -
> - /*
> - * Domains without a backing DM, don't have an ioreq page. Just
> - * point to a struct on the stack, initialising the state as needed.
> - */
> - if ( !p )
> - {
> - has_dm = 0;
> - p = &_ioreq;
> - p->state = STATE_IOREQ_NONE;
> - }
>
> /* Check for paged out page */
> ram_page = get_page_from_gfn(curr->domain, ram_gfn, &p2mt, P2M_UNSHARE);
> @@ -173,15 +160,6 @@ static int hvmemul_do_io(
> return X86EMUL_UNHANDLEABLE;
> }
>
> - if ( p->state != STATE_IOREQ_NONE )
> - {
> - gdprintk(XENLOG_WARNING, "WARNING: io already pending (%d)?\n",
> - p->state);
> - if ( ram_page )
> - put_page(ram_page);
> - return X86EMUL_UNHANDLEABLE;
> - }
> -
> vio->io_state =
> (p_data == NULL) ? HVMIO_dispatched : HVMIO_awaiting_completion;
> vio->io_size = size;
> @@ -193,6 +171,7 @@ static int hvmemul_do_io(
> if ( vio->mmio_retrying )
> *reps = 1;
>
> + p->state = STATE_IOREQ_NONE;
> p->dir = dir;
> p->data_is_ptr = value_is_ptr;
> p->type = is_mmio ? IOREQ_TYPE_COPY : IOREQ_TYPE_PIO;
> @@ -232,20 +211,15 @@ static int hvmemul_do_io(
> vio->io_state = HVMIO_handle_mmio_awaiting_completion;
> break;
> case X86EMUL_UNHANDLEABLE:
> - /* If there is no backing DM, just ignore accesses */
> - if ( !has_dm )
> + rc = X86EMUL_RETRY;
> + if ( !hvm_send_assist_req(curr, p) )
> {
> rc = X86EMUL_OKAY;
> vio->io_state = HVMIO_none;
> }
> - else
> - {
> - rc = X86EMUL_RETRY;
> - if ( !hvm_send_assist_req(curr) )
> - vio->io_state = HVMIO_none;
> - else if ( p_data == NULL )
> - rc = X86EMUL_OKAY;
> - }
> + else if ( p_data == NULL )
> + rc = X86EMUL_OKAY;
> +
> break;
> default:
> BUG();
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 69f7e74..71a44db 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -345,6 +345,14 @@ void hvm_migrate_pirqs(struct vcpu *v)
> spin_unlock(&d->event_lock);
> }
>
> +static ioreq_t *get_ioreq(struct vcpu *v)
> +{
> + struct domain *d = v->domain;
> + shared_iopage_t *p = d->arch.hvm_domain.ioreq.va;
newline here...
> + ASSERT((v == current) || spin_is_locked(&d->arch.hvm_domain.ioreq.lock));
.. and here. (I realise that this is just code motion, but might as
well take the opportunity to fix the style.)
> + return p ? &p->vcpu_ioreq[v->vcpu_id] : NULL;
> +}
> +
> void hvm_do_resume(struct vcpu *v)
> {
> ioreq_t *p;
> @@ -1287,7 +1295,86 @@ void hvm_vcpu_down(struct vcpu *v)
> }
> }
>
> -bool_t hvm_send_assist_req(struct vcpu *v)
> +int hvm_buffered_io_send(ioreq_t *p)
> +{
> + struct vcpu *v = current;
> + struct hvm_ioreq_page *iorp = &v->domain->arch.hvm_domain.buf_ioreq;
> + buffered_iopage_t *pg = iorp->va;
> + buf_ioreq_t bp;
> + /* Timeoffset sends 64b data, but no address. Use two consecutive slots.
> */
> + int qw = 0;
> +
> + /* Ensure buffered_iopage fits in a page */
> + BUILD_BUG_ON(sizeof(buffered_iopage_t) > PAGE_SIZE);
> +
> + /*
> + * Return 0 for the cases we can't deal with:
> + * - 'addr' is only a 20-bit field, so we cannot address beyond 1MB
> + * - we cannot buffer accesses to guest memory buffers, as the guest
> + * may expect the memory buffer to be synchronously accessed
> + * - the count field is usually used with data_is_ptr and since we don't
> + * support data_is_ptr we do not waste space for the count field
> either
> + */
> + if ( (p->addr > 0xffffful) || p->data_is_ptr || (p->count != 1) )
> + return 0;
> +
> + bp.type = p->type;
> + bp.dir = p->dir;
> + switch ( p->size )
> + {
> + case 1:
> + bp.size = 0;
> + break;
> + case 2:
> + bp.size = 1;
> + break;
> + case 4:
> + bp.size = 2;
> + break;
> + case 8:
> + bp.size = 3;
> + qw = 1;
> + break;
> + default:
> + gdprintk(XENLOG_WARNING, "unexpected ioreq size: %u\n", p->size);
> + return 0;
> + }
> +
> + bp.data = p->data;
> + bp.addr = p->addr;
> +
> + spin_lock(&iorp->lock);
> +
> + if ( (pg->write_pointer - pg->read_pointer) >=
> + (IOREQ_BUFFER_SLOT_NUM - qw) )
> + {
> + /* The queue is full: send the iopacket through the normal path. */
> + spin_unlock(&iorp->lock);
> + return 0;
> + }
> +
> + memcpy(&pg->buf_ioreq[pg->write_pointer % IOREQ_BUFFER_SLOT_NUM],
> + &bp, sizeof(bp));
> +
> + if ( qw )
> + {
> + bp.data = p->data >> 32;
> + memcpy(&pg->buf_ioreq[(pg->write_pointer+1) % IOREQ_BUFFER_SLOT_NUM],
> + &bp, sizeof(bp));
> + }
> +
> + /* Make the ioreq_t visible /before/ write_pointer. */
> + wmb();
> + pg->write_pointer += qw ? 2 : 1;
> +
> + notify_via_xen_event_channel(v->domain,
> + v->domain->arch.hvm_domain.params[HVM_PARAM_BUFIOREQ_EVTCHN]);
> + spin_unlock(&iorp->lock);
> +
> + return 1;
> +}
> +
> +bool_t hvm_send_assist_req(struct vcpu *v, ioreq_t *proto_p)
> {
> ioreq_t *p;
>
> @@ -1305,6 +1392,15 @@ bool_t hvm_send_assist_req(struct vcpu *v)
> return 0;
> }
>
> + p->dir = proto_p->dir;
> + p->data_is_ptr = proto_p->data_is_ptr;
> + p->type = proto_p->type;
> + p->size = proto_p->size;
> + p->addr = proto_p->addr;
> + p->count = proto_p->count;
> + p->df = proto_p->df;
> + p->data = proto_p->data;
> +
> prepare_wait_on_xen_event_channel(v->arch.hvm_vcpu.xen_port);
>
> /*
> diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
> index bf6309d..576641c 100644
> --- a/xen/arch/x86/hvm/io.c
> +++ b/xen/arch/x86/hvm/io.c
> @@ -46,85 +46,6 @@
> #include <xen/iocap.h>
> #include <public/hvm/ioreq.h>
>
> -int hvm_buffered_io_send(ioreq_t *p)
> -{
> - struct vcpu *v = current;
> - struct hvm_ioreq_page *iorp = &v->domain->arch.hvm_domain.buf_ioreq;
> - buffered_iopage_t *pg = iorp->va;
> - buf_ioreq_t bp;
> - /* Timeoffset sends 64b data, but no address. Use two consecutive slots.
> */
> - int qw = 0;
> -
> - /* Ensure buffered_iopage fits in a page */
> - BUILD_BUG_ON(sizeof(buffered_iopage_t) > PAGE_SIZE);
> -
> - /*
> - * Return 0 for the cases we can't deal with:
> - * - 'addr' is only a 20-bit field, so we cannot address beyond 1MB
> - * - we cannot buffer accesses to guest memory buffers, as the guest
> - * may expect the memory buffer to be synchronously accessed
> - * - the count field is usually used with data_is_ptr and since we don't
> - * support data_is_ptr we do not waste space for the count field
> either
> - */
> - if ( (p->addr > 0xffffful) || p->data_is_ptr || (p->count != 1) )
> - return 0;
> -
> - bp.type = p->type;
> - bp.dir = p->dir;
> - switch ( p->size )
> - {
> - case 1:
> - bp.size = 0;
> - break;
> - case 2:
> - bp.size = 1;
> - break;
> - case 4:
> - bp.size = 2;
> - break;
> - case 8:
> - bp.size = 3;
> - qw = 1;
> - break;
> - default:
> - gdprintk(XENLOG_WARNING, "unexpected ioreq size: %u\n", p->size);
> - return 0;
> - }
> -
> - bp.data = p->data;
> - bp.addr = p->addr;
> -
> - spin_lock(&iorp->lock);
> -
> - if ( (pg->write_pointer - pg->read_pointer) >=
> - (IOREQ_BUFFER_SLOT_NUM - qw) )
> - {
> - /* The queue is full: send the iopacket through the normal path. */
> - spin_unlock(&iorp->lock);
> - return 0;
> - }
> -
> - memcpy(&pg->buf_ioreq[pg->write_pointer % IOREQ_BUFFER_SLOT_NUM],
> - &bp, sizeof(bp));
> -
> - if ( qw )
> - {
> - bp.data = p->data >> 32;
> - memcpy(&pg->buf_ioreq[(pg->write_pointer+1) % IOREQ_BUFFER_SLOT_NUM],
> - &bp, sizeof(bp));
> - }
> -
> - /* Make the ioreq_t visible /before/ write_pointer. */
> - wmb();
> - pg->write_pointer += qw ? 2 : 1;
> -
> - notify_via_xen_event_channel(v->domain,
> - v->domain->arch.hvm_domain.params[HVM_PARAM_BUFIOREQ_EVTCHN]);
> - spin_unlock(&iorp->lock);
> -
> - return 1;
> -}
> -
> void send_timeoffset_req(unsigned long timeoff)
> {
> ioreq_t p[1];
> @@ -150,25 +71,14 @@ void send_timeoffset_req(unsigned long timeoff)
> void send_invalidate_req(void)
> {
> struct vcpu *v = current;
> - ioreq_t *p = get_ioreq(v);
> -
> - if ( !p )
> - return;
> -
> - if ( p->state != STATE_IOREQ_NONE )
> - {
> - gdprintk(XENLOG_ERR, "WARNING: send invalidate req with something "
> - "already pending (%d)?\n", p->state);
> - domain_crash(v->domain);
> - return;
> - }
> + ioreq_t p[1];
This can all be reduced to a single item, and even using C structure
initialisation rather than 4 explicit assignments.
~Andrew
>
> p->type = IOREQ_TYPE_INVALIDATE;
> p->size = 4;
> p->dir = IOREQ_WRITE;
> p->data = ~0UL; /* flush all */
>
> - (void)hvm_send_assist_req(v);
> + (void)hvm_send_assist_req(v, p);
> }
>
> int handle_mmio(void)
> diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
> index ccca5df..4e8fee8 100644
> --- a/xen/include/asm-x86/hvm/hvm.h
> +++ b/xen/include/asm-x86/hvm/hvm.h
> @@ -26,6 +26,7 @@
> #include <asm/hvm/asid.h>
> #include <public/domctl.h>
> #include <public/hvm/save.h>
> +#include <public/hvm/ioreq.h>
> #include <asm/mm.h>
>
> /* Interrupt acknowledgement sources. */
> @@ -223,7 +224,7 @@ int prepare_ring_for_helper(struct domain *d, unsigned
> long gmfn,
> struct page_info **_page, void **_va);
> void destroy_ring_for_helper(void **_va, struct page_info *page);
>
> -bool_t hvm_send_assist_req(struct vcpu *v);
> +bool_t hvm_send_assist_req(struct vcpu *v, ioreq_t *p);
>
> void hvm_get_guest_pat(struct vcpu *v, u64 *guest_pat);
> int hvm_set_guest_pat(struct vcpu *v, u64 guest_pat);
> diff --git a/xen/include/asm-x86/hvm/support.h
> b/xen/include/asm-x86/hvm/support.h
> index 3529499..b6af3c5 100644
> --- a/xen/include/asm-x86/hvm/support.h
> +++ b/xen/include/asm-x86/hvm/support.h
> @@ -22,19 +22,10 @@
> #define __ASM_X86_HVM_SUPPORT_H__
>
> #include <xen/types.h>
> -#include <public/hvm/ioreq.h>
> #include <xen/sched.h>
> #include <xen/hvm/save.h>
> #include <asm/processor.h>
>
> -static inline ioreq_t *get_ioreq(struct vcpu *v)
> -{
> - struct domain *d = v->domain;
> - shared_iopage_t *p = d->arch.hvm_domain.ioreq.va;
> - ASSERT((v == current) || spin_is_locked(&d->arch.hvm_domain.ioreq.lock));
> - return p ? &p->vcpu_ioreq[v->vcpu_id] : NULL;
> -}
> -
> #define HVM_DELIVER_NO_ERROR_CODE -1
>
> #ifndef NDEBUG
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