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    Subject[RFC Part2 PATCH 12/30] crypto ccp: handle the legacy SEV command when SNP is enabled
    Date
    The behavior of the SEV-legacy commands is altered when the SNP firmware
    is in the INIT state. When SNP is in INIT state, all the SEV-legacy
    commands that cause the firmware to write to memory must be in the
    firmware state before issuing the command..

    See SEV-SNP spec section 5.3.7 for more detail.

    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Joerg Roedel <jroedel@suse.de>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Tony Luck <tony.luck@intel.com>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: Tom Lendacky <thomas.lendacky@amd.com>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Sean Christopherson <seanjc@google.com>
    Cc: x86@kernel.org
    Cc: kvm@vger.kernel.org
    Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    ---
    drivers/crypto/ccp/sev-dev.c | 90 +++++++++++++++++++++++++++++++++---
    drivers/crypto/ccp/sev-dev.h | 1 +
    2 files changed, 85 insertions(+), 6 deletions(-)

    diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
    index 242c4775eb56..4aa9d4505d71 100644
    --- a/drivers/crypto/ccp/sev-dev.c
    +++ b/drivers/crypto/ccp/sev-dev.c
    @@ -148,12 +148,35 @@ static int sev_cmd_buffer_len(int cmd)
    return 0;
    }

    +static bool sev_legacy_cmd_buf_writable(int cmd)
    +{
    + switch (cmd) {
    + case SEV_CMD_PLATFORM_STATUS:
    + case SEV_CMD_GUEST_STATUS:
    + case SEV_CMD_LAUNCH_START:
    + case SEV_CMD_RECEIVE_START:
    + case SEV_CMD_LAUNCH_MEASURE:
    + case SEV_CMD_SEND_START:
    + case SEV_CMD_SEND_UPDATE_DATA:
    + case SEV_CMD_SEND_UPDATE_VMSA:
    + case SEV_CMD_PEK_CSR:
    + case SEV_CMD_PDH_CERT_EXPORT:
    + case SEV_CMD_GET_ID:
    + return true;
    + default:
    + return false;
    + }
    +}
    +
    static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
    {
    + size_t cmd_buf_len = sev_cmd_buffer_len(cmd);
    struct psp_device *psp = psp_master;
    struct sev_device *sev;
    unsigned int phys_lsb, phys_msb;
    unsigned int reg, ret = 0;
    + struct page *cmd_page = NULL;
    + struct rmpupdate e = {};

    if (!psp || !psp->sev_data)
    return -ENODEV;
    @@ -163,15 +186,47 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)

    sev = psp->sev_data;

    + /*
    + * Check If SNP is initialized and we are asked to execute a legacy
    + * command that requires write by the firmware in the command buffer.
    + * In that case use an intermediate command buffer page to complete the
    + * operation.
    + *
    + * NOTE: If the command buffer contains a pointer which will be modified
    + * by the firmware then caller must take care of it.
    + */
    + if (sev->snp_inited && sev_legacy_cmd_buf_writable(cmd)) {
    + cmd_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
    + if (!cmd_page)
    + return -ENOMEM;
    +
    + memcpy(page_address(cmd_page), data, cmd_buf_len);
    +
    + /* make it as a firmware page */
    + e.immutable = true;
    + e.assigned = true;
    + ret = rmptable_rmpupdate(cmd_page, &e);
    + if (ret) {
    + dev_err(sev->dev, "sev cmd id %#x, failed to change to firmware state (spa 0x%lx ret %d).\n",
    + cmd, page_to_pfn(cmd_page) << PAGE_SHIFT, ret);
    + goto e_free;
    + }
    + }
    +
    /* Get the physical address of the command buffer */
    - phys_lsb = data ? lower_32_bits(__psp_pa(data)) : 0;
    - phys_msb = data ? upper_32_bits(__psp_pa(data)) : 0;
    + if (cmd_page) {
    + phys_lsb = data ? lower_32_bits(__sme_page_pa(cmd_page)) : 0;
    + phys_msb = data ? upper_32_bits(__sme_page_pa(cmd_page)) : 0;
    + } else {
    + phys_lsb = data ? lower_32_bits(__psp_pa(data)) : 0;
    + phys_msb = data ? upper_32_bits(__psp_pa(data)) : 0;
    + }

    dev_dbg(sev->dev, "sev command id %#x buffer 0x%08x%08x timeout %us\n",
    cmd, phys_msb, phys_lsb, psp_timeout);

    print_hex_dump_debug("(in): ", DUMP_PREFIX_OFFSET, 16, 2, data,
    - sev_cmd_buffer_len(cmd), false);
    + cmd_buf_len, false);

    iowrite32(phys_lsb, sev->io_regs + sev->vdata->cmdbuff_addr_lo_reg);
    iowrite32(phys_msb, sev->io_regs + sev->vdata->cmdbuff_addr_hi_reg);
    @@ -185,6 +240,24 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)

    /* wait for command completion */
    ret = sev_wait_cmd_ioc(sev, &reg, psp_timeout);
    +
    + /* if an intermediate page is used then copy the data back to original. */
    + if (cmd_page) {
    + int rc;
    +
    + /* make it as a hypervisor page */
    + memset(&e, 0, sizeof(struct rmpupdate));
    + rc = rmptable_rmpupdate(cmd_page, &e);
    + if (rc) {
    + dev_err(sev->dev, "sev cmd id %#x, failed to change to hypervisor state ret=%d.\n",
    + cmd, rc);
    + /* Set the command page to NULL so that the page is leaked. */
    + cmd_page = NULL;
    + } else {
    + memcpy(data, page_address(cmd_page), cmd_buf_len);
    + }
    + }
    +
    if (ret) {
    if (psp_ret)
    *psp_ret = 0;
    @@ -192,7 +265,7 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
    dev_err(sev->dev, "sev command %#x timed out, disabling PSP\n", cmd);
    psp_dead = true;

    - return ret;
    + goto e_free;
    }

    psp_timeout = psp_cmd_timeout;
    @@ -207,8 +280,11 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
    }

    print_hex_dump_debug("(out): ", DUMP_PREFIX_OFFSET, 16, 2, data,
    - sev_cmd_buffer_len(cmd), false);
    + cmd_buf_len, false);

    +e_free:
    + if (cmd_page)
    + __free_page(cmd_page);
    return ret;
    }

    @@ -234,7 +310,7 @@ static int __sev_platform_init_locked(int *error)

    sev = psp->sev_data;

    - if (sev->state == SEV_STATE_INIT)
    + if (sev->legacy_inited && (sev->state == SEV_STATE_INIT))
    return 0;

    if (sev_es_tmr) {
    @@ -255,6 +331,7 @@ static int __sev_platform_init_locked(int *error)
    if (rc)
    return rc;

    + sev->legacy_inited = true;
    sev->state = SEV_STATE_INIT;

    /* Prepare for first SEV guest launch after INIT */
    @@ -289,6 +366,7 @@ static int __sev_platform_shutdown_locked(int *error)
    if (ret)
    return ret;

    + sev->legacy_inited = false;
    sev->state = SEV_STATE_UNINIT;
    dev_dbg(sev->dev, "SEV firmware shutdown\n");

    diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h
    index 18b116a817ff..2ee9665a901d 100644
    --- a/drivers/crypto/ccp/sev-dev.h
    +++ b/drivers/crypto/ccp/sev-dev.h
    @@ -54,6 +54,7 @@ struct sev_device {
    u8 build;

    bool snp_inited;
    + bool legacy_inited;
    };

    int sev_dev_init(struct psp_device *psp);
    --
    2.17.1
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