From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration 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 Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/mips/lib/bitops.c | 162 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 162 insertions(+) create mode 100644 arch/mips/lib/bitops.c (limited to 'arch/mips/lib/bitops.c') diff --git a/arch/mips/lib/bitops.c b/arch/mips/lib/bitops.c new file mode 100644 index 000000000..00aee98e9 --- /dev/null +++ b/arch/mips/lib/bitops.c @@ -0,0 +1,162 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (c) 1994-1997, 99, 2000, 06, 07 Ralf Baechle (ralf@linux-mips.org) + * Copyright (c) 1999, 2000 Silicon Graphics, Inc. + */ +#include +#include +#include +#include + + +/** + * __mips_set_bit - Atomically set a bit in memory. This is called by + * set_bit() if it cannot find a faster solution. + * @nr: the bit to set + * @addr: the address to start counting from + */ +void __mips_set_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + + mask = 1UL << bit; + raw_local_irq_save(flags); + *a |= mask; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL(__mips_set_bit); + + +/** + * __mips_clear_bit - Clears a bit in memory. This is called by clear_bit() if + * it cannot find a faster solution. + * @nr: Bit to clear + * @addr: Address to start counting from + */ +void __mips_clear_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + + mask = 1UL << bit; + raw_local_irq_save(flags); + *a &= ~mask; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL(__mips_clear_bit); + + +/** + * __mips_change_bit - Toggle a bit in memory. This is called by change_bit() + * if it cannot find a faster solution. + * @nr: Bit to change + * @addr: Address to start counting from + */ +void __mips_change_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + + mask = 1UL << bit; + raw_local_irq_save(flags); + *a ^= mask; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL(__mips_change_bit); + + +/** + * __mips_test_and_set_bit_lock - Set a bit and return its old value. This is + * called by test_and_set_bit_lock() if it cannot find a faster solution. + * @nr: Bit to set + * @addr: Address to count from + */ +int __mips_test_and_set_bit_lock(unsigned long nr, + volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + int res; + + mask = 1UL << bit; + raw_local_irq_save(flags); + res = (mask & *a) != 0; + *a |= mask; + raw_local_irq_restore(flags); + return res; +} +EXPORT_SYMBOL(__mips_test_and_set_bit_lock); + + +/** + * __mips_test_and_clear_bit - Clear a bit and return its old value. This is + * called by test_and_clear_bit() if it cannot find a faster solution. + * @nr: Bit to clear + * @addr: Address to count from + */ +int __mips_test_and_clear_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + int res; + + mask = 1UL << bit; + raw_local_irq_save(flags); + res = (mask & *a) != 0; + *a &= ~mask; + raw_local_irq_restore(flags); + return res; +} +EXPORT_SYMBOL(__mips_test_and_clear_bit); + + +/** + * __mips_test_and_change_bit - Change a bit and return its old value. This is + * called by test_and_change_bit() if it cannot find a faster solution. + * @nr: Bit to change + * @addr: Address to count from + */ +int __mips_test_and_change_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + int res; + + mask = 1UL << bit; + raw_local_irq_save(flags); + res = (mask & *a) != 0; + *a ^= mask; + raw_local_irq_restore(flags); + return res; +} +EXPORT_SYMBOL(__mips_test_and_change_bit); + +bool __mips_xor_is_negative_byte(unsigned long mask, + volatile unsigned long *addr) +{ + unsigned long flags; + unsigned long data; + + raw_local_irq_save(flags); + data = *addr; + *addr = data ^ mask; + raw_local_irq_restore(flags); + + return (data & BIT(7)) != 0; +} -- cgit v1.3.1