From: Ian Jackson <ian.jackson@citrix.com>
To: Paul Durrant <paul@xen.org>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
Paul Durrant <pdurrant@amazon.com>, Wei Liu <wl@xen.org>,
Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v4 5/5] tools/libxc: make use of domain context SHARED_INFO record...
Date: Thu, 21 May 2020 14:34:19 +0100 [thread overview]
Message-ID: <24262.33627.309482.955954@mariner.uk.xensource.com> (raw)
In-Reply-To: <20200521085932.10508-6-paul@xen.org>
Paul Durrant writes ("[PATCH v4 5/5] tools/libxc: make use of domain context SHARED_INFO record..."):
> ... in the save/restore code.
>
> This patch replaces direct mapping of the shared_info_frame (retrieved
> using XEN_DOMCTL_getdomaininfo) with save/load of the domain context
> SHARED_INFO record.
>
> No modifications are made to the definition of the migration stream at
> this point. Subsequent patches will define a record in the libxc domain
> image format for passing domain context and convert the save/restore code
> to use that.
Andy, I think this needs your option.
Thanks,
Ian.
> Signed-off-by: Paul Durrant <pdurrant@amazon.com>
> ---
> Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> Cc: Wei Liu <wl@xen.org>
>
> v3:
> - Moved basic get/set domain context functions to common code
>
> v2:
> - Re-based (now making use of DOMAIN_SAVE_FLAG_IGNORE)
> ---
> tools/libxc/xc_sr_common.c | 67 +++++++++++++++++++++++++++
> tools/libxc/xc_sr_common.h | 11 ++++-
> tools/libxc/xc_sr_common_x86_pv.c | 74 ++++++++++++++++++++++++++++++
> tools/libxc/xc_sr_common_x86_pv.h | 3 ++
> tools/libxc/xc_sr_restore_x86_pv.c | 26 ++++-------
> tools/libxc/xc_sr_save_x86_pv.c | 43 ++++++++---------
> tools/libxc/xg_save_restore.h | 1 +
> 7 files changed, 181 insertions(+), 44 deletions(-)
>
> diff --git a/tools/libxc/xc_sr_common.c b/tools/libxc/xc_sr_common.c
> index dd9a11b4b5..1acb3765aa 100644
> --- a/tools/libxc/xc_sr_common.c
> +++ b/tools/libxc/xc_sr_common.c
> @@ -138,6 +138,73 @@ int read_record(struct xc_sr_context *ctx, int fd, struct xc_sr_record *rec)
> return 0;
> };
>
> +int get_domain_context(struct xc_sr_context *ctx)
> +{
> + xc_interface *xch = ctx->xch;
> + size_t len = 0;
> + int rc;
> +
> + if ( ctx->domain_context.buffer )
> + {
> + ERROR("Domain context already present");
> + return -1;
> + }
> +
> + rc = xc_domain_getcontext(xch, ctx->domid, NULL, &len);
> + if ( rc < 0 )
> + {
> + PERROR("Unable to get size of domain context");
> + return -1;
> + }
> +
> + ctx->domain_context.buffer = malloc(len);
> + if ( !ctx->domain_context.buffer )
> + {
> + PERROR("Unable to allocate memory for domain context");
> + return -1;
> + }
> +
> + rc = xc_domain_getcontext(xch, ctx->domid, ctx->domain_context.buffer,
> + &len);
> + if ( rc < 0 )
> + {
> + PERROR("Unable to get domain context");
> + return -1;
> + }
> +
> + ctx->domain_context.len = len;
> +
> + return 0;
> +}
> +
> +int set_domain_context(struct xc_sr_context *ctx)
> +{
> + xc_interface *xch = ctx->xch;
> + int rc;
> +
> + if ( !ctx->domain_context.buffer )
> + {
> + ERROR("Domain context not present");
> + return -1;
> + }
> +
> + rc = xc_domain_setcontext(xch, ctx->domid, ctx->domain_context.buffer,
> + ctx->domain_context.len);
> +
> + if ( rc < 0 )
> + {
> + PERROR("Unable to set domain context");
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> +void common_cleanup(struct xc_sr_context *ctx)
> +{
> + free(ctx->domain_context.buffer);
> +}
> +
> static void __attribute__((unused)) build_assertions(void)
> {
> BUILD_BUG_ON(sizeof(struct xc_sr_ihdr) != 24);
> diff --git a/tools/libxc/xc_sr_common.h b/tools/libxc/xc_sr_common.h
> index 5dd51ccb15..0d61978b08 100644
> --- a/tools/libxc/xc_sr_common.h
> +++ b/tools/libxc/xc_sr_common.h
> @@ -208,6 +208,11 @@ struct xc_sr_context
>
> xc_dominfo_t dominfo;
>
> + struct {
> + void *buffer;
> + unsigned int len;
> + } domain_context;
> +
> union /* Common save or restore data. */
> {
> struct /* Save data. */
> @@ -314,7 +319,7 @@ struct xc_sr_context
> /* The guest pfns containing the p2m leaves */
> xen_pfn_t *p2m_pfns;
>
> - /* Read-only mapping of guests shared info page */
> + /* Pointer to shared_info (located in context buffer) */
> shared_info_any_t *shinfo;
>
> /* p2m generation count for verifying validity of local p2m. */
> @@ -425,6 +430,10 @@ int read_record(struct xc_sr_context *ctx, int fd, struct xc_sr_record *rec);
> int populate_pfns(struct xc_sr_context *ctx, unsigned int count,
> const xen_pfn_t *original_pfns, const uint32_t *types);
>
> +int get_domain_context(struct xc_sr_context *ctx);
> +int set_domain_context(struct xc_sr_context *ctx);
> +void common_cleanup(struct xc_sr_context *ctx);
> +
> #endif
> /*
> * Local variables:
> diff --git a/tools/libxc/xc_sr_common_x86_pv.c b/tools/libxc/xc_sr_common_x86_pv.c
> index d3d425cb82..69d9b142b8 100644
> --- a/tools/libxc/xc_sr_common_x86_pv.c
> +++ b/tools/libxc/xc_sr_common_x86_pv.c
> @@ -182,6 +182,80 @@ int x86_pv_map_m2p(struct xc_sr_context *ctx)
> return rc;
> }
>
> +int x86_pv_get_shinfo(struct xc_sr_context *ctx)
> +{
> + xc_interface *xch = ctx->xch;
> + unsigned int off = 0;
> + int rc;
> +
> +#define GET_PTR(_x) \
> + do { \
> + if ( ctx->domain_context.len - off < sizeof(*(_x)) ) \
> + { \
> + ERROR("Need another %lu bytes of context, only %u available\n", \
> + sizeof(*(_x)), ctx->domain_context.len - off); \
> + return -1; \
> + } \
> + (_x) = ctx->domain_context.buffer + off; \
> + } while (false);
> +
> + rc = get_domain_context(ctx);
> + if ( rc )
> + return rc;
> +
> + for ( ; ; )
> + {
> + struct domain_save_descriptor *desc;
> +
> + GET_PTR(desc);
> +
> + off += sizeof(*desc);
> +
> + switch (desc->typecode)
> + {
> + case DOMAIN_SAVE_CODE(SHARED_INFO):
> + {
> + DOMAIN_SAVE_TYPE(SHARED_INFO) *s;
> +
> + GET_PTR(s);
> +
> + ctx->x86.pv.shinfo = (shared_info_any_t *)s->buffer;
> + break;
> + }
> + default:
> + break;
> + }
> +
> + if ( desc->typecode == DOMAIN_SAVE_CODE(END) )
> + break;
> +
> + off += desc->length;
> + }
> +
> + if ( !ctx->x86.pv.shinfo )
> + {
> + ERROR("Failed to get SHARED_INFO\n");
> + return -1;
> + }
> +
> + return 0;
> +
> +#undef GET_PTR
> +}
> +
> +int x86_pv_set_shinfo(struct xc_sr_context *ctx)
> +{
> + xc_interface *xch = ctx->xch;
> +
> + if ( !ctx->x86.pv.shinfo )
> + {
> + ERROR("SHARED_INFO buffer not present\n");
> + return -1;
> + }
> +
> + return set_domain_context(ctx);
> +}
> +
> /*
> * Local variables:
> * mode: C
> diff --git a/tools/libxc/xc_sr_common_x86_pv.h b/tools/libxc/xc_sr_common_x86_pv.h
> index 2ed03309af..01442f48fb 100644
> --- a/tools/libxc/xc_sr_common_x86_pv.h
> +++ b/tools/libxc/xc_sr_common_x86_pv.h
> @@ -97,6 +97,9 @@ int x86_pv_domain_info(struct xc_sr_context *ctx);
> */
> int x86_pv_map_m2p(struct xc_sr_context *ctx);
>
> +int x86_pv_get_shinfo(struct xc_sr_context *ctx);
> +int x86_pv_set_shinfo(struct xc_sr_context *ctx);
> +
> #endif
> /*
> * Local variables:
> diff --git a/tools/libxc/xc_sr_restore_x86_pv.c b/tools/libxc/xc_sr_restore_x86_pv.c
> index 904ccc462a..21982a38ad 100644
> --- a/tools/libxc/xc_sr_restore_x86_pv.c
> +++ b/tools/libxc/xc_sr_restore_x86_pv.c
> @@ -865,7 +865,7 @@ static int handle_shared_info(struct xc_sr_context *ctx,
> xc_interface *xch = ctx->xch;
> unsigned int i;
> int rc = -1;
> - shared_info_any_t *guest_shinfo = NULL;
> + shared_info_any_t *guest_shinfo;
> const shared_info_any_t *old_shinfo = rec->data;
>
> if ( !ctx->x86.pv.restore.seen_pv_info )
> @@ -878,18 +878,14 @@ static int handle_shared_info(struct xc_sr_context *ctx,
> {
> ERROR("X86_PV_SHARED_INFO record wrong size: length %u"
> ", expected 4096", rec->length);
> - goto err;
> + return -1;
> }
>
> - guest_shinfo = xc_map_foreign_range(
> - xch, ctx->domid, PAGE_SIZE, PROT_READ | PROT_WRITE,
> - ctx->dominfo.shared_info_frame);
> - if ( !guest_shinfo )
> - {
> - PERROR("Failed to map Shared Info at mfn %#lx",
> - ctx->dominfo.shared_info_frame);
> - goto err;
> - }
> + rc = x86_pv_get_shinfo(ctx);
> + if ( rc )
> + return rc;
> +
> + guest_shinfo = ctx->x86.pv.shinfo;
>
> MEMCPY_FIELD(guest_shinfo, old_shinfo, vcpu_info, ctx->x86.pv.width);
> MEMCPY_FIELD(guest_shinfo, old_shinfo, arch, ctx->x86.pv.width);
> @@ -904,13 +900,7 @@ static int handle_shared_info(struct xc_sr_context *ctx,
>
> MEMSET_ARRAY_FIELD(guest_shinfo, evtchn_mask, 0xff, ctx->x86.pv.width);
>
> - rc = 0;
> -
> - err:
> - if ( guest_shinfo )
> - munmap(guest_shinfo, PAGE_SIZE);
> -
> - return rc;
> + return x86_pv_set_shinfo(ctx);
> }
>
> /* restore_ops function. */
> diff --git a/tools/libxc/xc_sr_save_x86_pv.c b/tools/libxc/xc_sr_save_x86_pv.c
> index f3ccf5bb4b..bf87789340 100644
> --- a/tools/libxc/xc_sr_save_x86_pv.c
> +++ b/tools/libxc/xc_sr_save_x86_pv.c
> @@ -9,25 +9,6 @@ static inline bool is_canonical_address(xen_vaddr_t vaddr)
> return ((int64_t)vaddr >> 47) == ((int64_t)vaddr >> 63);
> }
>
> -/*
> - * Maps the guests shared info page.
> - */
> -static int map_shinfo(struct xc_sr_context *ctx)
> -{
> - xc_interface *xch = ctx->xch;
> -
> - ctx->x86.pv.shinfo = xc_map_foreign_range(
> - xch, ctx->domid, PAGE_SIZE, PROT_READ, ctx->dominfo.shared_info_frame);
> - if ( !ctx->x86.pv.shinfo )
> - {
> - PERROR("Failed to map shared info frame at mfn %#lx",
> - ctx->dominfo.shared_info_frame);
> - return -1;
> - }
> -
> - return 0;
> -}
> -
> /*
> * Copy a list of mfns from a guest, accounting for differences between guest
> * and toolstack width. Can fail if truncation would occur.
> @@ -854,13 +835,26 @@ static int write_x86_pv_p2m_frames(struct xc_sr_context *ctx)
> */
> static int write_shared_info(struct xc_sr_context *ctx)
> {
> + xc_interface *xch = ctx->xch;
> struct xc_sr_record rec = {
> .type = REC_TYPE_SHARED_INFO,
> .length = PAGE_SIZE,
> - .data = ctx->x86.pv.shinfo,
> };
> + int rc;
>
> - return write_record(ctx, &rec);
> + if ( !(rec.data = calloc(1, PAGE_SIZE)) )
> + {
> + ERROR("Cannot allocate buffer for SHARED_INFO data");
> + return -1;
> + }
> +
> + memcpy(rec.data, ctx->x86.pv.shinfo, sizeof(*ctx->x86.pv.shinfo));
> +
> + rc = write_record(ctx, &rec);
> +
> + free(rec.data);
> +
> + return rc;
> }
>
> /*
> @@ -1041,7 +1035,7 @@ static int x86_pv_setup(struct xc_sr_context *ctx)
> if ( rc )
> return rc;
>
> - rc = map_shinfo(ctx);
> + rc = x86_pv_get_shinfo(ctx);
> if ( rc )
> return rc;
>
> @@ -1112,12 +1106,11 @@ static int x86_pv_cleanup(struct xc_sr_context *ctx)
> if ( ctx->x86.pv.p2m )
> munmap(ctx->x86.pv.p2m, ctx->x86.pv.p2m_frames * PAGE_SIZE);
>
> - if ( ctx->x86.pv.shinfo )
> - munmap(ctx->x86.pv.shinfo, PAGE_SIZE);
> -
> if ( ctx->x86.pv.m2p )
> munmap(ctx->x86.pv.m2p, ctx->x86.pv.nr_m2p_frames * PAGE_SIZE);
>
> + common_cleanup(ctx);
> +
> return 0;
> }
>
> diff --git a/tools/libxc/xg_save_restore.h b/tools/libxc/xg_save_restore.h
> index 303081df0d..296b523963 100644
> --- a/tools/libxc/xg_save_restore.h
> +++ b/tools/libxc/xg_save_restore.h
> @@ -19,6 +19,7 @@
>
> #include <xen/foreign/x86_32.h>
> #include <xen/foreign/x86_64.h>
> +#include <xen/save.h>
>
> /*
> ** We process save/restore/migrate in batches of pages; the below
> --
> 2.20.1
>
prev parent reply other threads:[~2020-05-21 13:34 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 8:59 [PATCH v4 0/5] domain context infrastructure Paul Durrant
2020-05-21 8:59 ` [PATCH v4 1/5] xen/common: introduce a new framework for save/restore of 'domain' context Paul Durrant
2020-05-21 14:58 ` Julien Grall
2020-05-21 8:59 ` [PATCH v4 2/5] xen/common/domctl: introduce XEN_DOMCTL_get/setdomaincontext Paul Durrant
2020-05-21 15:04 ` Julien Grall
2020-05-21 8:59 ` [PATCH v4 3/5] tools/misc: add xen-domctx to present domain context Paul Durrant
2020-05-21 13:33 ` Ian Jackson
2020-05-21 8:59 ` [PATCH v4 4/5] common/domain: add a domain context record for shared_info Paul Durrant
2020-05-21 15:13 ` Julien Grall
2020-05-21 15:25 ` Paul Durrant
2020-05-21 16:00 ` Paul Durrant
2020-05-21 16:02 ` Julien Grall
2020-05-21 8:59 ` [PATCH v4 5/5] tools/libxc: make use of domain context SHARED_INFO record Paul Durrant
2020-05-21 13:34 ` Ian Jackson [this message]
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