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    Subject[PATCH RFC v7 28/64] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled
    Date
    From: Brijesh Singh <brijesh.singh@amd.com>

    The behavior and requirement for the SEV-legacy command is altered when
    the SNP firmware is in the INIT state. See SEV-SNP firmware specification
    for more details.

    Allocate the Trusted Memory Region (TMR) as a 2mb sized/aligned region
    when SNP is enabled to satisfy new requirements for the SNP. Continue
    allocating a 1mb region for !SNP configuration.

    While at it, provide API that can be used by others to allocate a page
    that can be used by the firmware. The immediate user for this API will
    be the KVM driver. The KVM driver to need to allocate a firmware context
    page during the guest creation. The context page need to be updated
    by the firmware. See the SEV-SNP specification for further details.

    Co-developed-by: Ashish Kalra <ashish.kalra@amd.com>
    Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
    Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    Signed-off-by: Michael Roth <michael.roth@amd.com>
    ---
    drivers/crypto/ccp/sev-dev.c | 148 +++++++++++++++++++++++++++++++++--
    include/linux/psp-sev.h | 9 +++
    2 files changed, 149 insertions(+), 8 deletions(-)

    diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
    index eca4e59b0f44..4c12e98a1219 100644
    --- a/drivers/crypto/ccp/sev-dev.c
    +++ b/drivers/crypto/ccp/sev-dev.c
    @@ -94,6 +94,13 @@ static void *sev_init_ex_buffer;
    */
    struct sev_data_range_list *snp_range_list;

    +/* When SEV-SNP is enabled the TMR needs to be 2MB aligned and 2MB size. */
    +#define SEV_SNP_ES_TMR_SIZE (2 * 1024 * 1024)
    +
    +static size_t sev_es_tmr_size = SEV_ES_TMR_SIZE;
    +
    +static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret);
    +
    static inline bool sev_version_greater_or_equal(u8 maj, u8 min)
    {
    struct sev_device *sev = psp_master->sev_data;
    @@ -216,11 +223,134 @@ void snp_mark_pages_offline(unsigned long pfn, unsigned int npages)
    }
    EXPORT_SYMBOL_GPL(snp_mark_pages_offline);

    +static int snp_reclaim_pages(unsigned long paddr, unsigned int npages, bool locked)
    +{
    + /* Cbit maybe set in the paddr */
    + unsigned long pfn = __sme_clr(paddr) >> PAGE_SHIFT;
    + int ret, err, i, n = 0;
    +
    + if (!pfn_valid(pfn)) {
    + pr_err("%s: Invalid PFN %lx\n", __func__, pfn);
    + return 0;
    + }
    +
    + for (i = 0; i < npages; i++, pfn++, n++) {
    + paddr = pfn << PAGE_SHIFT;
    +
    + if (locked)
    + ret = __sev_do_cmd_locked(SEV_CMD_SNP_PAGE_RECLAIM, &paddr, &err);
    + else
    + ret = sev_do_cmd(SEV_CMD_SNP_PAGE_RECLAIM, &paddr, &err);
    +
    + if (ret)
    + goto cleanup;
    +
    + ret = rmp_make_shared(pfn, PG_LEVEL_4K);
    + if (ret)
    + goto cleanup;
    + }
    +
    + return 0;
    +
    +cleanup:
    + /*
    + * If failed to reclaim the page then page is no longer safe to
    + * be release back to the system, leak it.
    + */
    + snp_mark_pages_offline(pfn, npages - n);
    + return ret;
    +}
    +
    +static int rmp_mark_pages_firmware(unsigned long paddr, unsigned int npages, bool locked)
    +{
    + /* Cbit maybe set in the paddr */
    + unsigned long pfn = __sme_clr(paddr) >> PAGE_SHIFT;
    + int rc, n = 0, i;
    +
    + for (i = 0; i < npages; i++, n++, pfn++) {
    + rc = rmp_make_private(pfn, 0, PG_LEVEL_4K, 0, true);
    + if (rc)
    + goto cleanup;
    + }
    +
    + return 0;
    +
    +cleanup:
    + /*
    + * Try unrolling the firmware state changes by
    + * reclaiming the pages which were already changed to the
    + * firmware state.
    + */
    + snp_reclaim_pages(paddr, n, locked);
    +
    + return rc;
    +}
    +
    +static struct page *__snp_alloc_firmware_pages(gfp_t gfp_mask, int order, bool locked)
    +{
    + unsigned long npages = 1ul << order, paddr;
    + struct sev_device *sev;
    + struct page *page;
    +
    + if (!psp_master || !psp_master->sev_data)
    + return NULL;
    +
    + page = alloc_pages(gfp_mask, order);
    + if (!page)
    + return NULL;
    +
    + /* If SEV-SNP is initialized then add the page in RMP table. */
    + sev = psp_master->sev_data;
    + if (!sev->snp_initialized)
    + return page;
    +
    + paddr = __pa((unsigned long)page_address(page));
    + if (rmp_mark_pages_firmware(paddr, npages, locked))
    + return NULL;
    +
    + return page;
    +}
    +
    +void *snp_alloc_firmware_page(gfp_t gfp_mask)
    +{
    + struct page *page;
    +
    + page = __snp_alloc_firmware_pages(gfp_mask, 0, false);
    +
    + return page ? page_address(page) : NULL;
    +}
    +EXPORT_SYMBOL_GPL(snp_alloc_firmware_page);
    +
    +static void __snp_free_firmware_pages(struct page *page, int order, bool locked)
    +{
    + struct sev_device *sev = psp_master->sev_data;
    + unsigned long paddr, npages = 1ul << order;
    +
    + if (!page)
    + return;
    +
    + paddr = __pa((unsigned long)page_address(page));
    + if (sev->snp_initialized &&
    + snp_reclaim_pages(paddr, npages, locked))
    + return;
    +
    + __free_pages(page, order);
    +}
    +
    +void snp_free_firmware_page(void *addr)
    +{
    + if (!addr)
    + return;
    +
    + __snp_free_firmware_pages(virt_to_page(addr), 0, false);
    +}
    +EXPORT_SYMBOL_GPL(snp_free_firmware_page);
    +
    static void *sev_fw_alloc(unsigned long len)
    {
    struct page *page;

    - page = alloc_pages(GFP_KERNEL, get_order(len));
    + page = __snp_alloc_firmware_pages(GFP_KERNEL, get_order(len), false);
    if (!page)
    return NULL;

    @@ -468,7 +598,7 @@ static int __sev_init_locked(int *error)
    data.tmr_address = __pa(sev_es_tmr);

    data.flags |= SEV_INIT_FLAGS_SEV_ES;
    - data.tmr_len = SEV_ES_TMR_SIZE;
    + data.tmr_len = sev_es_tmr_size;
    }

    return __sev_do_cmd_locked(SEV_CMD_INIT, &data, error);
    @@ -491,7 +621,7 @@ static int __sev_init_ex_locked(int *error)
    data.tmr_address = __pa(sev_es_tmr);

    data.flags |= SEV_INIT_FLAGS_SEV_ES;
    - data.tmr_len = SEV_ES_TMR_SIZE;
    + data.tmr_len = sev_es_tmr_size;
    }

    return __sev_do_cmd_locked(SEV_CMD_INIT_EX, &data, error);
    @@ -982,6 +1112,8 @@ static int __sev_snp_init_locked(int *error)
    sev->snp_initialized = true;
    dev_dbg(sev->dev, "SEV-SNP firmware initialized\n");

    + sev_es_tmr_size = SEV_SNP_ES_TMR_SIZE;
    +
    return rc;
    }

    @@ -1499,8 +1631,9 @@ static void sev_firmware_shutdown(struct sev_device *sev)
    /* The TMR area was encrypted, flush it from the cache */
    wbinvd_on_all_cpus();

    - free_pages((unsigned long)sev_es_tmr,
    - get_order(SEV_ES_TMR_SIZE));
    + __snp_free_firmware_pages(virt_to_page(sev_es_tmr),
    + get_order(sev_es_tmr_size),
    + false);
    sev_es_tmr = NULL;
    }

    @@ -1511,8 +1644,7 @@ static void sev_firmware_shutdown(struct sev_device *sev)
    }

    if (snp_range_list) {
    - free_pages((unsigned long)snp_range_list,
    - get_order(PAGE_SIZE));
    + snp_free_firmware_page(snp_range_list);
    snp_range_list = NULL;
    }

    @@ -1593,7 +1725,7 @@ void sev_pci_init(void)
    }

    /* Obtain the TMR memory area for SEV-ES use */
    - sev_es_tmr = sev_fw_alloc(SEV_ES_TMR_SIZE);
    + sev_es_tmr = sev_fw_alloc(sev_es_tmr_size);
    if (!sev_es_tmr)
    dev_warn(sev->dev,
    "SEV: TMR allocation failed, SEV-ES support unavailable\n");
    diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
    index 8edf5c548fbf..d19744807471 100644
    --- a/include/linux/psp-sev.h
    +++ b/include/linux/psp-sev.h
    @@ -922,6 +922,8 @@ int sev_guest_decommission(struct sev_data_decommission *data, int *error);
    int sev_do_cmd(int cmd, void *data, int *psp_ret);

    void *psp_copy_user_blob(u64 uaddr, u32 len);
    +void *snp_alloc_firmware_page(gfp_t mask);
    +void snp_free_firmware_page(void *addr);

    /**
    * sev_mark_pages_offline - insert non-reclaimed firmware/guest pages
    @@ -959,6 +961,13 @@ static inline void *psp_copy_user_blob(u64 __user uaddr, u32 len) { return ERR_P

    void snp_mark_pages_offline(unsigned long pfn, unsigned int npages) {}

    +static inline void *snp_alloc_firmware_page(gfp_t mask)
    +{
    + return NULL;
    +}
    +
    +static inline void snp_free_firmware_page(void *addr) { }
    +
    #endif /* CONFIG_CRYPTO_DEV_SP_PSP */

    #endif /* __PSP_SEV_H__ */
    --
    2.25.1
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