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    Subject[PATCH Part2 v5 14/45] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled
    Date
    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 satify 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.

    Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    ---
    drivers/crypto/ccp/sev-dev.c | 169 ++++++++++++++++++++++++++++++++++-
    include/linux/psp-sev.h | 11 +++
    2 files changed, 176 insertions(+), 4 deletions(-)

    diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
    index 01edad9116f2..34dc358b13b9 100644
    --- a/drivers/crypto/ccp/sev-dev.c
    +++ b/drivers/crypto/ccp/sev-dev.c
    @@ -62,6 +62,14 @@ static int psp_timeout;
    #define SEV_ES_TMR_SIZE (1024 * 1024)
    static void *sev_es_tmr;

    +/* 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 int sev_do_cmd(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;
    @@ -159,6 +167,156 @@ static int sev_cmd_buffer_len(int cmd)
    return 0;
    }

    +static void snp_leak_pages(unsigned long pfn, unsigned int npages)
    +{
    + WARN(1, "psc failed, pfn 0x%lx pages %d (leaking)\n", pfn, npages);
    + while (npages--) {
    + memory_failure(pfn, 0);
    + dump_rmpentry(pfn);
    + pfn++;
    + }
    +}
    +
    +static int snp_reclaim_pages(unsigned long pfn, unsigned int npages, bool locked)
    +{
    + struct sev_data_snp_page_reclaim data;
    + int ret, err, i, n = 0;
    +
    + for (i = 0; i < npages; i++) {
    + memset(&data, 0, sizeof(data));
    + data.paddr = pfn << PAGE_SHIFT;
    +
    + if (locked)
    + ret = __sev_do_cmd_locked(SEV_CMD_SNP_PAGE_RECLAIM, &data, &err);
    + else
    + ret = sev_do_cmd(SEV_CMD_SNP_PAGE_RECLAIM, &data, &err);
    + if (ret)
    + goto cleanup;
    +
    + ret = rmp_make_shared(pfn, PG_LEVEL_4K);
    + if (ret)
    + goto cleanup;
    +
    + pfn++;
    + n++;
    + }
    +
    + return 0;
    +
    +cleanup:
    + /*
    + * If failed to reclaim the page then page is no longer safe to
    + * be released, leak it.
    + */
    + snp_leak_pages(pfn, npages - n);
    + return ret;
    +}
    +
    +static inline int rmp_make_firmware(unsigned long pfn, int level)
    +{
    + return rmp_make_private(pfn, 0, level, 0, true);
    +}
    +
    +static int snp_set_rmp_state(unsigned long paddr, unsigned int npages, bool to_fw, bool locked,
    + bool need_reclaim)
    +{
    + unsigned long pfn = __sme_clr(paddr) >> PAGE_SHIFT; /* Cbit maybe set in the paddr */
    + int rc, n = 0, i;
    +
    + for (i = 0; i < npages; i++) {
    + if (to_fw)
    + rc = rmp_make_firmware(pfn, PG_LEVEL_4K);
    + else
    + rc = need_reclaim ? snp_reclaim_pages(pfn, 1, locked) :
    + rmp_make_shared(pfn, PG_LEVEL_4K);
    + if (rc)
    + goto cleanup;
    +
    + pfn++;
    + n++;
    + }
    +
    + return 0;
    +
    +cleanup:
    + /* Try unrolling the firmware state changes */
    + if (to_fw) {
    + /*
    + * Reclaim the pages which were already changed to the
    + * firmware state.
    + */
    + snp_reclaim_pages(paddr >> PAGE_SHIFT, n, locked);
    +
    + return rc;
    + }
    +
    + /*
    + * If failed to change the page state to shared, then its not safe
    + * to release the page back to the system, leak it.
    + */
    + snp_leak_pages(pfn, npages - n);
    +
    + 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 ERR_PTR(-EINVAL);
    +
    + 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_inited)
    + return page;
    +
    + paddr = __pa((unsigned long)page_address(page));
    + if (snp_set_rmp_state(paddr, npages, true, locked, false))
    + 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)
    +{
    + unsigned long paddr, npages = 1ul << order;
    +
    + if (!page)
    + return;
    +
    + paddr = __pa((unsigned long)page_address(page));
    + if (snp_set_rmp_state(paddr, npages, false, locked, true))
    + 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(snp_free_firmware_page);
    +
    static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
    {
    struct psp_device *psp = psp_master;
    @@ -281,7 +439,7 @@ static int __sev_platform_init_locked(int *error)

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

    rc = __sev_do_cmd_locked(SEV_CMD_INIT, &data, error);
    @@ -638,6 +796,8 @@ static int __sev_snp_init_locked(int *error)
    sev->snp_inited = true;
    dev_dbg(sev->dev, "SEV-SNP firmware initialized\n");

    + sev_es_tmr_size = SEV_SNP_ES_TMR_SIZE;
    +
    return rc;
    }

    @@ -1161,8 +1321,9 @@ 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;
    }

    @@ -1233,7 +1394,7 @@ void sev_pci_init(void)
    }

    /* Obtain the TMR memory area for SEV-ES use */
    - tmr_page = alloc_pages(GFP_KERNEL, get_order(SEV_ES_TMR_SIZE));
    + tmr_page = __snp_alloc_firmware_pages(GFP_KERNEL, get_order(sev_es_tmr_size), false);
    if (tmr_page) {
    sev_es_tmr = page_address(tmr_page);
    } else {
    diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
    index f2105a8755f9..00bd684dc094 100644
    --- a/include/linux/psp-sev.h
    +++ b/include/linux/psp-sev.h
    @@ -12,6 +12,8 @@
    #ifndef __PSP_SEV_H__
    #define __PSP_SEV_H__

    +#include <linux/sev.h>
    +
    #include <uapi/linux/psp-sev.h>

    #ifdef CONFIG_X86
    @@ -919,6 +921,8 @@ int snp_guest_page_reclaim(struct sev_data_snp_page_reclaim *data, int *error);
    int snp_guest_dbg_decrypt(struct sev_data_snp_dbg *data, int *error);

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

    #else /* !CONFIG_CRYPTO_DEV_SP_PSP */

    @@ -960,6 +964,13 @@ static inline int snp_guest_dbg_decrypt(struct sev_data_snp_dbg *data, int *erro
    return -ENODEV;
    }

    +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__ */
    --
    2.17.1
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