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, 353 insertions, 0 deletions

diff --git a/arch/mips/math-emu/me-debugfs.c b/arch/mips/math-emu/me-debugfs.c
new file mode 100644
index 000000000..aeddf7aec
--- /dev/null
+++ b/arch/mips/math-emu/me-debugfs.c
@@ -0,0 +1,353 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/cpumask.h>
+#include <linux/debugfs.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/percpu.h>
+#include <linux/types.h>
+#include <asm/debug.h>
+#include <asm/fpu_emulator.h>
+#include <asm/local.h>
+
+DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);
+
+static int fpuemu_stat_get(void *data, u64 *val)
+{
+	int cpu;
+	unsigned long sum = 0;
+
+	for_each_online_cpu(cpu) {
+		struct mips_fpu_emulator_stats *ps;
+		local_t *pv;
+
+		ps = &per_cpu(fpuemustats, cpu);
+		pv = (void *)ps + (unsigned long)data;
+		sum += local_read(pv);
+	}
+	*val = sum;
+	return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(fops_fpuemu_stat, fpuemu_stat_get, NULL, "%llu\n");
+
+/*
+ * Used to obtain names for a debugfs instruction counter, given field name
+ * in fpuemustats structure. For example, for input "cmp_sueq_d", the output
+ * would be "cmp.sueq.d". This is needed since dots are not allowed to be
+ * used in structure field names, and are, on the other hand, desired to be
+ * used in debugfs item names to be clearly associated to corresponding
+ * MIPS FPU instructions.
+ */
+static void adjust_instruction_counter_name(char *out_name, char *in_name, size_t len)
+{
+	int i = 0;
+
+	strscpy(out_name, in_name, len);
+	while (in_name[i] != '\0') {
+		if (out_name[i] == '_')
+			out_name[i] = '.';
+		i++;
+	}
+}
+
+static int fpuemustats_clear_show(struct seq_file *s, void *unused)
+{
+	__this_cpu_write((fpuemustats).emulated, 0);
+	__this_cpu_write((fpuemustats).loads, 0);
+	__this_cpu_write((fpuemustats).stores, 0);
+	__this_cpu_write((fpuemustats).branches, 0);
+	__this_cpu_write((fpuemustats).cp1ops, 0);
+	__this_cpu_write((fpuemustats).cp1xops, 0);
+	__this_cpu_write((fpuemustats).errors, 0);
+	__this_cpu_write((fpuemustats).ieee754_inexact, 0);
+	__this_cpu_write((fpuemustats).ieee754_underflow, 0);
+	__this_cpu_write((fpuemustats).ieee754_overflow, 0);
+	__this_cpu_write((fpuemustats).ieee754_zerodiv, 0);
+	__this_cpu_write((fpuemustats).ieee754_invalidop, 0);
+	__this_cpu_write((fpuemustats).ds_emul, 0);
+
+	__this_cpu_write((fpuemustats).abs_s, 0);
+	__this_cpu_write((fpuemustats).abs_d, 0);
+	__this_cpu_write((fpuemustats).add_s, 0);
+	__this_cpu_write((fpuemustats).add_d, 0);
+	__this_cpu_write((fpuemustats).bc1eqz, 0);
+	__this_cpu_write((fpuemustats).bc1nez, 0);
+	__this_cpu_write((fpuemustats).ceil_w_s, 0);
+	__this_cpu_write((fpuemustats).ceil_w_d, 0);
+	__this_cpu_write((fpuemustats).ceil_l_s, 0);
+	__this_cpu_write((fpuemustats).ceil_l_d, 0);
+	__this_cpu_write((fpuemustats).class_s, 0);
+	__this_cpu_write((fpuemustats).class_d, 0);
+	__this_cpu_write((fpuemustats).cmp_af_s, 0);
+	__this_cpu_write((fpuemustats).cmp_af_d, 0);
+	__this_cpu_write((fpuemustats).cmp_eq_s, 0);
+	__this_cpu_write((fpuemustats).cmp_eq_d, 0);
+	__this_cpu_write((fpuemustats).cmp_le_s, 0);
+	__this_cpu_write((fpuemustats).cmp_le_d, 0);
+	__this_cpu_write((fpuemustats).cmp_lt_s, 0);
+	__this_cpu_write((fpuemustats).cmp_lt_d, 0);
+	__this_cpu_write((fpuemustats).cmp_ne_s, 0);
+	__this_cpu_write((fpuemustats).cmp_ne_d, 0);
+	__this_cpu_write((fpuemustats).cmp_or_s, 0);
+	__this_cpu_write((fpuemustats).cmp_or_d, 0);
+	__this_cpu_write((fpuemustats).cmp_ueq_s, 0);
+	__this_cpu_write((fpuemustats).cmp_ueq_d, 0);
+	__this_cpu_write((fpuemustats).cmp_ule_s, 0);
+	__this_cpu_write((fpuemustats).cmp_ule_d, 0);
+	__this_cpu_write((fpuemustats).cmp_ult_s, 0);
+	__this_cpu_write((fpuemustats).cmp_ult_d, 0);
+	__this_cpu_write((fpuemustats).cmp_un_s, 0);
+	__this_cpu_write((fpuemustats).cmp_un_d, 0);
+	__this_cpu_write((fpuemustats).cmp_une_s, 0);
+	__this_cpu_write((fpuemustats).cmp_une_d, 0);
+	__this_cpu_write((fpuemustats).cmp_saf_s, 0);
+	__this_cpu_write((fpuemustats).cmp_saf_d, 0);
+	__this_cpu_write((fpuemustats).cmp_seq_s, 0);
+	__this_cpu_write((fpuemustats).cmp_seq_d, 0);
+	__this_cpu_write((fpuemustats).cmp_sle_s, 0);
+	__this_cpu_write((fpuemustats).cmp_sle_d, 0);
+	__this_cpu_write((fpuemustats).cmp_slt_s, 0);
+	__this_cpu_write((fpuemustats).cmp_slt_d, 0);
+	__this_cpu_write((fpuemustats).cmp_sne_s, 0);
+	__this_cpu_write((fpuemustats).cmp_sne_d, 0);
+	__this_cpu_write((fpuemustats).cmp_sor_s, 0);
+	__this_cpu_write((fpuemustats).cmp_sor_d, 0);
+	__this_cpu_write((fpuemustats).cmp_sueq_s, 0);
+	__this_cpu_write((fpuemustats).cmp_sueq_d, 0);
+	__this_cpu_write((fpuemustats).cmp_sule_s, 0);
+	__this_cpu_write((fpuemustats).cmp_sule_d, 0);
+	__this_cpu_write((fpuemustats).cmp_sult_s, 0);
+	__this_cpu_write((fpuemustats).cmp_sult_d, 0);
+	__this_cpu_write((fpuemustats).cmp_sun_s, 0);
+	__this_cpu_write((fpuemustats).cmp_sun_d, 0);
+	__this_cpu_write((fpuemustats).cmp_sune_s, 0);
+	__this_cpu_write((fpuemustats).cmp_sune_d, 0);
+	__this_cpu_write((fpuemustats).cvt_d_l, 0);
+	__this_cpu_write((fpuemustats).cvt_d_s, 0);
+	__this_cpu_write((fpuemustats).cvt_d_w, 0);
+	__this_cpu_write((fpuemustats).cvt_l_s, 0);
+	__this_cpu_write((fpuemustats).cvt_l_d, 0);
+	__this_cpu_write((fpuemustats).cvt_s_d, 0);
+	__this_cpu_write((fpuemustats).cvt_s_l, 0);
+	__this_cpu_write((fpuemustats).cvt_s_w, 0);
+	__this_cpu_write((fpuemustats).cvt_w_s, 0);
+	__this_cpu_write((fpuemustats).cvt_w_d, 0);
+	__this_cpu_write((fpuemustats).div_s, 0);
+	__this_cpu_write((fpuemustats).div_d, 0);
+	__this_cpu_write((fpuemustats).floor_w_s, 0);
+	__this_cpu_write((fpuemustats).floor_w_d, 0);
+	__this_cpu_write((fpuemustats).floor_l_s, 0);
+	__this_cpu_write((fpuemustats).floor_l_d, 0);
+	__this_cpu_write((fpuemustats).maddf_s, 0);
+	__this_cpu_write((fpuemustats).maddf_d, 0);
+	__this_cpu_write((fpuemustats).max_s, 0);
+	__this_cpu_write((fpuemustats).max_d, 0);
+	__this_cpu_write((fpuemustats).maxa_s, 0);
+	__this_cpu_write((fpuemustats).maxa_d, 0);
+	__this_cpu_write((fpuemustats).min_s, 0);
+	__this_cpu_write((fpuemustats).min_d, 0);
+	__this_cpu_write((fpuemustats).mina_s, 0);
+	__this_cpu_write((fpuemustats).mina_d, 0);
+	__this_cpu_write((fpuemustats).mov_s, 0);
+	__this_cpu_write((fpuemustats).mov_d, 0);
+	__this_cpu_write((fpuemustats).msubf_s, 0);
+	__this_cpu_write((fpuemustats).msubf_d, 0);
+	__this_cpu_write((fpuemustats).mul_s, 0);
+	__this_cpu_write((fpuemustats).mul_d, 0);
+	__this_cpu_write((fpuemustats).neg_s, 0);
+	__this_cpu_write((fpuemustats).neg_d, 0);
+	__this_cpu_write((fpuemustats).recip_s, 0);
+	__this_cpu_write((fpuemustats).recip_d, 0);
+	__this_cpu_write((fpuemustats).rint_s, 0);
+	__this_cpu_write((fpuemustats).rint_d, 0);
+	__this_cpu_write((fpuemustats).round_w_s, 0);
+	__this_cpu_write((fpuemustats).round_w_d, 0);
+	__this_cpu_write((fpuemustats).round_l_s, 0);
+	__this_cpu_write((fpuemustats).round_l_d, 0);
+	__this_cpu_write((fpuemustats).rsqrt_s, 0);
+	__this_cpu_write((fpuemustats).rsqrt_d, 0);
+	__this_cpu_write((fpuemustats).sel_s, 0);
+	__this_cpu_write((fpuemustats).sel_d, 0);
+	__this_cpu_write((fpuemustats).seleqz_s, 0);
+	__this_cpu_write((fpuemustats).seleqz_d, 0);
+	__this_cpu_write((fpuemustats).selnez_s, 0);
+	__this_cpu_write((fpuemustats).selnez_d, 0);
+	__this_cpu_write((fpuemustats).sqrt_s, 0);
+	__this_cpu_write((fpuemustats).sqrt_d, 0);
+	__this_cpu_write((fpuemustats).sub_s, 0);
+	__this_cpu_write((fpuemustats).sub_d, 0);
+	__this_cpu_write((fpuemustats).trunc_w_s, 0);
+	__this_cpu_write((fpuemustats).trunc_w_d, 0);
+	__this_cpu_write((fpuemustats).trunc_l_s, 0);
+	__this_cpu_write((fpuemustats).trunc_l_d, 0);
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(fpuemustats_clear);
+
+static int __init debugfs_fpuemu(void)
+{
+	struct dentry *fpuemu_debugfs_base_dir;
+	struct dentry *fpuemu_debugfs_inst_dir;
+	char name[32];
+
+	fpuemu_debugfs_base_dir = debugfs_create_dir("fpuemustats",
+						     mips_debugfs_dir);
+
+	debugfs_create_file("fpuemustats_clear", 0444, mips_debugfs_dir, NULL,
+			    &fpuemustats_clear_fops);
+
+#define FPU_EMU_STAT_OFFSET(m)						\
+	offsetof(struct mips_fpu_emulator_stats, m)
+
+#define FPU_STAT_CREATE(m)						\
+do {									\
+	debugfs_create_file(#m, 0444, fpuemu_debugfs_base_dir,		\
+				(void *)FPU_EMU_STAT_OFFSET(m),		\
+				&fops_fpuemu_stat);			\
+} while (0)
+
+	FPU_STAT_CREATE(emulated);
+	FPU_STAT_CREATE(loads);
+	FPU_STAT_CREATE(stores);
+	FPU_STAT_CREATE(branches);
+	FPU_STAT_CREATE(cp1ops);
+	FPU_STAT_CREATE(cp1xops);
+	FPU_STAT_CREATE(errors);
+	FPU_STAT_CREATE(ieee754_inexact);
+	FPU_STAT_CREATE(ieee754_underflow);
+	FPU_STAT_CREATE(ieee754_overflow);
+	FPU_STAT_CREATE(ieee754_zerodiv);
+	FPU_STAT_CREATE(ieee754_invalidop);
+	FPU_STAT_CREATE(ds_emul);
+
+	fpuemu_debugfs_inst_dir = debugfs_create_dir("instructions",
+						     fpuemu_debugfs_base_dir);
+
+#define FPU_STAT_CREATE_EX(m)						\
+do {									\
+	adjust_instruction_counter_name(name, #m, sizeof(name));			\
+									\
+	debugfs_create_file(name, 0444, fpuemu_debugfs_inst_dir,	\
+				(void *)FPU_EMU_STAT_OFFSET(m),		\
+				&fops_fpuemu_stat);			\
+} while (0)
+
+	FPU_STAT_CREATE_EX(abs_s);
+	FPU_STAT_CREATE_EX(abs_d);
+	FPU_STAT_CREATE_EX(add_s);
+	FPU_STAT_CREATE_EX(add_d);
+	FPU_STAT_CREATE_EX(bc1eqz);
+	FPU_STAT_CREATE_EX(bc1nez);
+	FPU_STAT_CREATE_EX(ceil_w_s);
+	FPU_STAT_CREATE_EX(ceil_w_d);
+	FPU_STAT_CREATE_EX(ceil_l_s);
+	FPU_STAT_CREATE_EX(ceil_l_d);
+	FPU_STAT_CREATE_EX(class_s);
+	FPU_STAT_CREATE_EX(class_d);
+	FPU_STAT_CREATE_EX(cmp_af_s);
+	FPU_STAT_CREATE_EX(cmp_af_d);
+	FPU_STAT_CREATE_EX(cmp_eq_s);
+	FPU_STAT_CREATE_EX(cmp_eq_d);
+	FPU_STAT_CREATE_EX(cmp_le_s);
+	FPU_STAT_CREATE_EX(cmp_le_d);
+	FPU_STAT_CREATE_EX(cmp_lt_s);
+	FPU_STAT_CREATE_EX(cmp_lt_d);
+	FPU_STAT_CREATE_EX(cmp_ne_s);
+	FPU_STAT_CREATE_EX(cmp_ne_d);
+	FPU_STAT_CREATE_EX(cmp_or_s);
+	FPU_STAT_CREATE_EX(cmp_or_d);
+	FPU_STAT_CREATE_EX(cmp_ueq_s);
+	FPU_STAT_CREATE_EX(cmp_ueq_d);
+	FPU_STAT_CREATE_EX(cmp_ule_s);
+	FPU_STAT_CREATE_EX(cmp_ule_d);
+	FPU_STAT_CREATE_EX(cmp_ult_s);
+	FPU_STAT_CREATE_EX(cmp_ult_d);
+	FPU_STAT_CREATE_EX(cmp_un_s);
+	FPU_STAT_CREATE_EX(cmp_un_d);
+	FPU_STAT_CREATE_EX(cmp_une_s);
+	FPU_STAT_CREATE_EX(cmp_une_d);
+	FPU_STAT_CREATE_EX(cmp_saf_s);
+	FPU_STAT_CREATE_EX(cmp_saf_d);
+	FPU_STAT_CREATE_EX(cmp_seq_s);
+	FPU_STAT_CREATE_EX(cmp_seq_d);
+	FPU_STAT_CREATE_EX(cmp_sle_s);
+	FPU_STAT_CREATE_EX(cmp_sle_d);
+	FPU_STAT_CREATE_EX(cmp_slt_s);
+	FPU_STAT_CREATE_EX(cmp_slt_d);
+	FPU_STAT_CREATE_EX(cmp_sne_s);
+	FPU_STAT_CREATE_EX(cmp_sne_d);
+	FPU_STAT_CREATE_EX(cmp_sor_s);
+	FPU_STAT_CREATE_EX(cmp_sor_d);
+	FPU_STAT_CREATE_EX(cmp_sueq_s);
+	FPU_STAT_CREATE_EX(cmp_sueq_d);
+	FPU_STAT_CREATE_EX(cmp_sule_s);
+	FPU_STAT_CREATE_EX(cmp_sule_d);
+	FPU_STAT_CREATE_EX(cmp_sult_s);
+	FPU_STAT_CREATE_EX(cmp_sult_d);
+	FPU_STAT_CREATE_EX(cmp_sun_s);
+	FPU_STAT_CREATE_EX(cmp_sun_d);
+	FPU_STAT_CREATE_EX(cmp_sune_s);
+	FPU_STAT_CREATE_EX(cmp_sune_d);
+	FPU_STAT_CREATE_EX(cvt_d_l);
+	FPU_STAT_CREATE_EX(cvt_d_s);
+	FPU_STAT_CREATE_EX(cvt_d_w);
+	FPU_STAT_CREATE_EX(cvt_l_s);
+	FPU_STAT_CREATE_EX(cvt_l_d);
+	FPU_STAT_CREATE_EX(cvt_s_d);
+	FPU_STAT_CREATE_EX(cvt_s_l);
+	FPU_STAT_CREATE_EX(cvt_s_w);
+	FPU_STAT_CREATE_EX(cvt_w_s);
+	FPU_STAT_CREATE_EX(cvt_w_d);
+	FPU_STAT_CREATE_EX(div_s);
+	FPU_STAT_CREATE_EX(div_d);
+	FPU_STAT_CREATE_EX(floor_w_s);
+	FPU_STAT_CREATE_EX(floor_w_d);
+	FPU_STAT_CREATE_EX(floor_l_s);
+	FPU_STAT_CREATE_EX(floor_l_d);
+	FPU_STAT_CREATE_EX(maddf_s);
+	FPU_STAT_CREATE_EX(maddf_d);
+	FPU_STAT_CREATE_EX(max_s);
+	FPU_STAT_CREATE_EX(max_d);
+	FPU_STAT_CREATE_EX(maxa_s);
+	FPU_STAT_CREATE_EX(maxa_d);
+	FPU_STAT_CREATE_EX(min_s);
+	FPU_STAT_CREATE_EX(min_d);
+	FPU_STAT_CREATE_EX(mina_s);
+	FPU_STAT_CREATE_EX(mina_d);
+	FPU_STAT_CREATE_EX(mov_s);
+	FPU_STAT_CREATE_EX(mov_d);
+	FPU_STAT_CREATE_EX(msubf_s);
+	FPU_STAT_CREATE_EX(msubf_d);
+	FPU_STAT_CREATE_EX(mul_s);
+	FPU_STAT_CREATE_EX(mul_d);
+	FPU_STAT_CREATE_EX(neg_s);
+	FPU_STAT_CREATE_EX(neg_d);
+	FPU_STAT_CREATE_EX(recip_s);
+	FPU_STAT_CREATE_EX(recip_d);
+	FPU_STAT_CREATE_EX(rint_s);
+	FPU_STAT_CREATE_EX(rint_d);
+	FPU_STAT_CREATE_EX(round_w_s);
+	FPU_STAT_CREATE_EX(round_w_d);
+	FPU_STAT_CREATE_EX(round_l_s);
+	FPU_STAT_CREATE_EX(round_l_d);
+	FPU_STAT_CREATE_EX(rsqrt_s);
+	FPU_STAT_CREATE_EX(rsqrt_d);
+	FPU_STAT_CREATE_EX(sel_s);
+	FPU_STAT_CREATE_EX(sel_d);
+	FPU_STAT_CREATE_EX(seleqz_s);
+	FPU_STAT_CREATE_EX(seleqz_d);
+	FPU_STAT_CREATE_EX(selnez_s);
+	FPU_STAT_CREATE_EX(selnez_d);
+	FPU_STAT_CREATE_EX(sqrt_s);
+	FPU_STAT_CREATE_EX(sqrt_d);
+	FPU_STAT_CREATE_EX(sub_s);
+	FPU_STAT_CREATE_EX(sub_d);
+	FPU_STAT_CREATE_EX(trunc_w_s);
+	FPU_STAT_CREATE_EX(trunc_w_d);
+	FPU_STAT_CREATE_EX(trunc_l_s);
+	FPU_STAT_CREATE_EX(trunc_l_d);
+
+	return 0;
+}
+arch_initcall(debugfs_fpuemu);