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    Subject[PATCH V7 9/9] Drivers: hv : vmbus: Initialize VMbus ring buffer for Isolation VM
    Date
    From: Tianyu Lan <Tianyu.Lan@microsoft.com>

    VMbus ring buffer are shared with host and it's need to
    be accessed via extra address space of Isolation VM with
    AMD SNP support. This patch is to map the ring buffer
    address in extra address space via vmap_pfn(). Hyperv set
    memory host visibility hvcall smears data in the ring buffer
    and so reset the ring buffer memory to zero after mapping.

    Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
    ---
    Change since v4:
    * Use PFN_DOWN instead of HVPFN_DOWN in the hv_ringbuffer_init()

    Change since v3:
    * Remove hv_ringbuffer_post_init(), merge map
    operation for Isolation VM into hv_ringbuffer_init()
    * Call hv_ringbuffer_init() after __vmbus_establish_gpadl().
    ---
    drivers/hv/Kconfig | 1 +
    drivers/hv/channel.c | 19 +++++++-------
    drivers/hv/ring_buffer.c | 55 ++++++++++++++++++++++++++++++----------
    3 files changed, 53 insertions(+), 22 deletions(-)

    diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
    index d1123ceb38f3..dd12af20e467 100644
    --- a/drivers/hv/Kconfig
    +++ b/drivers/hv/Kconfig
    @@ -8,6 +8,7 @@ config HYPERV
    || (ARM64 && !CPU_BIG_ENDIAN))
    select PARAVIRT
    select X86_HV_CALLBACK_VECTOR if X86
    + select VMAP_PFN
    help
    Select this option to run Linux as a Hyper-V client operating
    system.
    diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
    index b37ff4a39224..dc5c35210c16 100644
    --- a/drivers/hv/channel.c
    +++ b/drivers/hv/channel.c
    @@ -683,15 +683,6 @@ static int __vmbus_open(struct vmbus_channel *newchannel,
    if (!newchannel->max_pkt_size)
    newchannel->max_pkt_size = VMBUS_DEFAULT_MAX_PKT_SIZE;

    - err = hv_ringbuffer_init(&newchannel->outbound, page, send_pages, 0);
    - if (err)
    - goto error_clean_ring;
    -
    - err = hv_ringbuffer_init(&newchannel->inbound, &page[send_pages],
    - recv_pages, newchannel->max_pkt_size);
    - if (err)
    - goto error_clean_ring;
    -
    /* Establish the gpadl for the ring buffer */
    newchannel->ringbuffer_gpadlhandle.gpadl_handle = 0;

    @@ -703,6 +694,16 @@ static int __vmbus_open(struct vmbus_channel *newchannel,
    if (err)
    goto error_clean_ring;

    + err = hv_ringbuffer_init(&newchannel->outbound,
    + page, send_pages, 0);
    + if (err)
    + goto error_free_gpadl;
    +
    + err = hv_ringbuffer_init(&newchannel->inbound, &page[send_pages],
    + recv_pages, newchannel->max_pkt_size);
    + if (err)
    + goto error_free_gpadl;
    +
    /* Create and init the channel open message */
    open_info = kzalloc(sizeof(*open_info) +
    sizeof(struct vmbus_channel_open_channel),
    diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
    index 314015d9e912..931802ae985c 100644
    --- a/drivers/hv/ring_buffer.c
    +++ b/drivers/hv/ring_buffer.c
    @@ -17,6 +17,8 @@
    #include <linux/vmalloc.h>
    #include <linux/slab.h>
    #include <linux/prefetch.h>
    +#include <linux/io.h>
    +#include <asm/mshyperv.h>

    #include "hyperv_vmbus.h"

    @@ -183,8 +185,10 @@ void hv_ringbuffer_pre_init(struct vmbus_channel *channel)
    int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
    struct page *pages, u32 page_cnt, u32 max_pkt_size)
    {
    - int i;
    struct page **pages_wraparound;
    + unsigned long *pfns_wraparound;
    + u64 pfn;
    + int i;

    BUILD_BUG_ON((sizeof(struct hv_ring_buffer) != PAGE_SIZE));

    @@ -192,23 +196,48 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
    * First page holds struct hv_ring_buffer, do wraparound mapping for
    * the rest.
    */
    - pages_wraparound = kcalloc(page_cnt * 2 - 1, sizeof(struct page *),
    - GFP_KERNEL);
    - if (!pages_wraparound)
    - return -ENOMEM;
    + if (hv_isolation_type_snp()) {
    + pfn = page_to_pfn(pages) +
    + PFN_DOWN(ms_hyperv.shared_gpa_boundary);
    +
    + pfns_wraparound = kcalloc(page_cnt * 2 - 1,
    + sizeof(unsigned long), GFP_KERNEL);
    + if (!pfns_wraparound)
    + return -ENOMEM;
    +
    + pfns_wraparound[0] = pfn;
    + for (i = 0; i < 2 * (page_cnt - 1); i++)
    + pfns_wraparound[i + 1] = pfn + i % (page_cnt - 1) + 1;

    - pages_wraparound[0] = pages;
    - for (i = 0; i < 2 * (page_cnt - 1); i++)
    - pages_wraparound[i + 1] = &pages[i % (page_cnt - 1) + 1];
    + ring_info->ring_buffer = (struct hv_ring_buffer *)
    + vmap_pfn(pfns_wraparound, page_cnt * 2 - 1,
    + PAGE_KERNEL);
    + kfree(pfns_wraparound);

    - ring_info->ring_buffer = (struct hv_ring_buffer *)
    - vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP, PAGE_KERNEL);
    + if (!ring_info->ring_buffer)
    + return -ENOMEM;
    +
    + /* Zero ring buffer after setting memory host visibility. */
    + memset(ring_info->ring_buffer, 0x00, PAGE_SIZE * page_cnt);
    + } else {
    + pages_wraparound = kcalloc(page_cnt * 2 - 1,
    + sizeof(struct page *),
    + GFP_KERNEL);
    +
    + pages_wraparound[0] = pages;
    + for (i = 0; i < 2 * (page_cnt - 1); i++)
    + pages_wraparound[i + 1] =
    + &pages[i % (page_cnt - 1) + 1];

    - kfree(pages_wraparound);
    + ring_info->ring_buffer = (struct hv_ring_buffer *)
    + vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP,
    + PAGE_KERNEL);

    + kfree(pages_wraparound);
    + if (!ring_info->ring_buffer)
    + return -ENOMEM;
    + }

    - if (!ring_info->ring_buffer)
    - return -ENOMEM;

    ring_info->ring_buffer->read_index =
    ring_info->ring_buffer->write_index = 0;
    --
    2.25.1
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