KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration")
Cc: stable@vger.kernel.org
Reported-by: Stefan Teodorescu <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 381 insertions, 0 deletions

diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c
new file mode 100644
index 000000000..b14ce5106
--- /dev/null
+++ b/drivers/crypto/ccp/psp-dev.c
@@ -0,0 +1,381 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AMD Platform Security Processor (PSP) interface
+ *
+ * Copyright (C) 2016,2019 Advanced Micro Devices, Inc.
+ *
+ * Author: Brijesh Singh <brijesh.singh@amd.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/irqreturn.h>
+#include <linux/mutex.h>
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+
+#include "sp-dev.h"
+#include "psp-dev.h"
+#include "sev-dev.h"
+#include "tee-dev.h"
+#include "sfs.h"
+#include "platform-access.h"
+#include "dbc.h"
+#include "hsti.h"
+
+struct psp_device *psp_master;
+
+#define PSP_C2PMSG_17_CMDRESP_CMD	GENMASK(19, 16)
+
+static int psp_mailbox_poll(const void __iomem *cmdresp_reg, unsigned int *cmdresp,
+			    unsigned int timeout_msecs)
+{
+	while (true) {
+		*cmdresp = ioread32(cmdresp_reg);
+		if (FIELD_GET(PSP_CMDRESP_RESP, *cmdresp))
+			return 0;
+
+		if (!timeout_msecs--)
+			break;
+
+		usleep_range(1000, 1100);
+	}
+
+	return -ETIMEDOUT;
+}
+
+int psp_mailbox_command(struct psp_device *psp, enum psp_cmd cmd, void *cmdbuff,
+			unsigned int timeout_msecs, unsigned int *cmdresp)
+{
+	void __iomem *cmdresp_reg, *cmdbuff_lo_reg, *cmdbuff_hi_reg;
+	int ret;
+
+	if (!psp || !psp->vdata || !psp->vdata->cmdresp_reg ||
+	    !psp->vdata->cmdbuff_addr_lo_reg || !psp->vdata->cmdbuff_addr_hi_reg)
+		return -ENODEV;
+
+	cmdresp_reg    = psp->io_regs + psp->vdata->cmdresp_reg;
+	cmdbuff_lo_reg = psp->io_regs + psp->vdata->cmdbuff_addr_lo_reg;
+	cmdbuff_hi_reg = psp->io_regs + psp->vdata->cmdbuff_addr_hi_reg;
+
+	mutex_lock(&psp->mailbox_mutex);
+
+	/* Ensure mailbox is ready for a command */
+	ret = -EBUSY;
+	if (psp_mailbox_poll(cmdresp_reg, cmdresp, 0))
+		goto unlock;
+
+	if (cmdbuff) {
+		iowrite32(lower_32_bits(__psp_pa(cmdbuff)), cmdbuff_lo_reg);
+		iowrite32(upper_32_bits(__psp_pa(cmdbuff)), cmdbuff_hi_reg);
+	}
+
+	*cmdresp = FIELD_PREP(PSP_C2PMSG_17_CMDRESP_CMD, cmd);
+	iowrite32(*cmdresp, cmdresp_reg);
+
+	ret = psp_mailbox_poll(cmdresp_reg, cmdresp, timeout_msecs);
+
+unlock:
+	mutex_unlock(&psp->mailbox_mutex);
+
+	return ret;
+}
+
+int psp_extended_mailbox_cmd(struct psp_device *psp, unsigned int timeout_msecs,
+			     struct psp_ext_request *req)
+{
+	unsigned int reg;
+	int ret;
+
+	print_hex_dump_debug("->psp ", DUMP_PREFIX_OFFSET, 16, 2, req,
+			     req->header.payload_size, false);
+
+	ret = psp_mailbox_command(psp, PSP_CMD_TEE_EXTENDED_CMD, (void *)req,
+				  timeout_msecs, &reg);
+	if (ret) {
+		return ret;
+	} else if (FIELD_GET(PSP_CMDRESP_STS, reg)) {
+		req->header.status = FIELD_GET(PSP_CMDRESP_STS, reg);
+		return -EIO;
+	}
+
+	print_hex_dump_debug("<-psp ", DUMP_PREFIX_OFFSET, 16, 2, req,
+			     req->header.payload_size, false);
+
+	return 0;
+}
+
+static struct psp_device *psp_alloc_struct(struct sp_device *sp)
+{
+	struct device *dev = sp->dev;
+	struct psp_device *psp;
+
+	psp = devm_kzalloc(dev, sizeof(*psp), GFP_KERNEL);
+	if (!psp)
+		return NULL;
+
+	psp->dev = dev;
+	psp->sp = sp;
+
+	snprintf(psp->name, sizeof(psp->name), "psp-%u", sp->ord);
+
+	return psp;
+}
+
+static irqreturn_t psp_irq_handler(int irq, void *data)
+{
+	struct psp_device *psp = data;
+	unsigned int status;
+
+	/* Read the interrupt status: */
+	status = ioread32(psp->io_regs + psp->vdata->intsts_reg);
+
+	/* Clear the interrupt status by writing the same value we read. */
+	iowrite32(status, psp->io_regs + psp->vdata->intsts_reg);
+
+	/* invoke subdevice interrupt handlers */
+	if (status) {
+		if (psp->sev_irq_handler)
+			psp->sev_irq_handler(irq, psp->sev_irq_data, status);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static unsigned int psp_get_capability(struct psp_device *psp)
+{
+	unsigned int val = ioread32(psp->io_regs + psp->vdata->feature_reg);
+
+	/*
+	 * Check for a access to the registers.  If this read returns
+	 * 0xffffffff, it's likely that the system is running a broken
+	 * BIOS which disallows access to the device. Stop here and
+	 * fail the PSP initialization (but not the load, as the CCP
+	 * could get properly initialized).
+	 */
+	if (val == 0xffffffff) {
+		dev_notice(psp->dev, "psp: unable to access the device: you might be running a broken BIOS.\n");
+		return -ENODEV;
+	}
+	psp->capability.raw = val;
+
+	return 0;
+}
+
+static int psp_check_sev_support(struct psp_device *psp)
+{
+	/* Check if device supports SEV feature */
+	if (!psp->capability.sev) {
+		dev_dbg(psp->dev, "psp does not support SEV\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int psp_check_tee_support(struct psp_device *psp)
+{
+	/* Check if device supports TEE feature */
+	if (!psp->capability.tee) {
+		dev_dbg(psp->dev, "psp does not support TEE\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int psp_check_sfs_support(struct psp_device *psp)
+{
+	/* Check if device supports SFS feature */
+	if (!psp->capability.sfs) {
+		dev_dbg(psp->dev, "psp does not support SFS\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int psp_init(struct psp_device *psp)
+{
+	int ret;
+
+	if (!psp_check_sev_support(psp)) {
+		ret = sev_dev_init(psp);
+		if (ret)
+			return ret;
+	}
+
+	if (!psp_check_tee_support(psp)) {
+		ret = tee_dev_init(psp);
+		if (ret)
+			return ret;
+	}
+
+	if (!psp_check_sfs_support(psp)) {
+		ret = sfs_dev_init(psp);
+		if (ret)
+			return ret;
+	}
+
+	if (psp->vdata->platform_access) {
+		ret = platform_access_dev_init(psp);
+		if (ret)
+			return ret;
+	}
+
+	/* dbc must come after platform access as it tests the feature */
+	if (PSP_FEATURE(psp, DBC) ||
+	    psp->capability.dbc_thru_ext) {
+		ret = dbc_dev_init(psp);
+		if (ret)
+			return ret;
+	}
+
+	/* HSTI uses platform access on some systems. */
+	ret = psp_init_hsti(psp);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+int psp_dev_init(struct sp_device *sp)
+{
+	struct device *dev = sp->dev;
+	struct psp_device *psp;
+	int ret;
+
+	ret = -ENOMEM;
+	psp = psp_alloc_struct(sp);
+	if (!psp)
+		goto e_err;
+
+	sp->psp_data = psp;
+
+	psp->vdata = (struct psp_vdata *)sp->dev_vdata->psp_vdata;
+	if (!psp->vdata) {
+		ret = -ENODEV;
+		dev_err(dev, "missing driver data\n");
+		goto e_err;
+	}
+
+	psp->io_regs = sp->io_map;
+	mutex_init(&psp->mailbox_mutex);
+
+	ret = psp_get_capability(psp);
+	if (ret)
+		goto e_disable;
+
+	/* Disable and clear interrupts until ready */
+	iowrite32(0, psp->io_regs + psp->vdata->inten_reg);
+	iowrite32(-1, psp->io_regs + psp->vdata->intsts_reg);
+
+	/* Request an irq */
+	ret = sp_request_psp_irq(psp->sp, psp_irq_handler, psp->name, psp);
+	if (ret) {
+		dev_err(dev, "psp: unable to allocate an IRQ\n");
+		goto e_err;
+	}
+
+	/* master device must be set for platform access */
+	if (psp->sp->set_psp_master_device)
+		psp->sp->set_psp_master_device(psp->sp);
+
+	ret = psp_init(psp);
+	if (ret)
+		goto e_irq;
+
+	/* Enable interrupt */
+	iowrite32(-1, psp->io_regs + psp->vdata->inten_reg);
+
+	dev_notice(dev, "psp enabled\n");
+
+	return 0;
+
+e_irq:
+	if (sp->clear_psp_master_device)
+		sp->clear_psp_master_device(sp);
+
+	sp_free_psp_irq(psp->sp, psp);
+e_err:
+	sp->psp_data = NULL;
+
+	dev_notice(dev, "psp initialization failed\n");
+
+	return ret;
+
+e_disable:
+	sp->psp_data = NULL;
+
+	return ret;
+}
+
+void psp_dev_destroy(struct sp_device *sp)
+{
+	struct psp_device *psp = sp->psp_data;
+
+	if (!psp)
+		return;
+
+	dbc_dev_destroy(psp);
+
+	platform_access_dev_destroy(psp);
+
+	sfs_dev_destroy(psp);
+
+	tee_dev_destroy(psp);
+
+	sev_dev_destroy(psp);
+
+	sp_free_psp_irq(sp, psp);
+
+	if (sp->clear_psp_master_device)
+		sp->clear_psp_master_device(sp);
+}
+
+void psp_set_sev_irq_handler(struct psp_device *psp, psp_irq_handler_t handler,
+			     void *data)
+{
+	psp->sev_irq_data = data;
+	psp->sev_irq_handler = handler;
+}
+
+void psp_clear_sev_irq_handler(struct psp_device *psp)
+{
+	psp_set_sev_irq_handler(psp, NULL, NULL);
+}
+
+struct psp_device *psp_get_master_device(void)
+{
+	struct sp_device *sp = sp_get_psp_master_device();
+
+	return sp ? sp->psp_data : NULL;
+}
+
+int psp_restore(struct sp_device *sp)
+{
+	struct psp_device *psp = sp->psp_data;
+	int ret = 0;
+
+	if (psp->tee_data)
+		ret = tee_restore(psp);
+
+	return ret;
+}
+
+void psp_pci_init(void)
+{
+	psp_master = psp_get_master_device();
+
+	if (!psp_master)
+		return;
+
+	sev_pci_init();
+}
+
+void psp_pci_exit(void)
+{
+	if (!psp_master)
+		return;
+
+	sev_pci_exit();
+}