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 --- drivers/net/phy/linkmode.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 95 insertions(+) create mode 100644 drivers/net/phy/linkmode.c (limited to 'drivers/net/phy/linkmode.c') diff --git a/drivers/net/phy/linkmode.c b/drivers/net/phy/linkmode.c new file mode 100644 index 000000000..f60560fe3 --- /dev/null +++ b/drivers/net/phy/linkmode.c @@ -0,0 +1,95 @@ +// SPDX-License-Identifier: GPL-2.0+ +#include + +/** + * linkmode_resolve_pause - resolve the allowable pause modes + * @local_adv: local advertisement in ethtool format + * @partner_adv: partner advertisement in ethtool format + * @tx_pause: pointer to bool to indicate whether transmit pause should be + * enabled. + * @rx_pause: pointer to bool to indicate whether receive pause should be + * enabled. + * + * Flow control is resolved according to our and the link partners + * advertisements using the following drawn from the 802.3 specs: + * Local device Link partner + * Pause AsymDir Pause AsymDir Result + * 0 X 0 X Disabled + * 0 1 1 0 Disabled + * 0 1 1 1 TX + * 1 0 0 X Disabled + * 1 X 1 X TX+RX + * 1 1 0 1 RX + */ +void linkmode_resolve_pause(const unsigned long *local_adv, + const unsigned long *partner_adv, + bool *tx_pause, bool *rx_pause) +{ + __ETHTOOL_DECLARE_LINK_MODE_MASK(m); + + linkmode_and(m, local_adv, partner_adv); + if (linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT, m)) { + *tx_pause = true; + *rx_pause = true; + } else if (linkmode_test_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, m)) { + *tx_pause = linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT, + partner_adv); + *rx_pause = linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT, + local_adv); + } else { + *tx_pause = false; + *rx_pause = false; + } +} +EXPORT_SYMBOL_GPL(linkmode_resolve_pause); + +/** + * linkmode_set_pause - set the pause mode advertisement + * @advertisement: advertisement in ethtool format + * @tx: boolean from ethtool struct ethtool_pauseparam tx_pause member + * @rx: boolean from ethtool struct ethtool_pauseparam rx_pause member + * + * Configure the advertised Pause and Asym_Pause bits according to the + * capabilities of provided in @tx and @rx. + * + * We convert as follows: + * tx rx Pause AsymDir + * 0 0 0 0 + * 0 1 1 1 + * 1 0 0 1 + * 1 1 1 0 + * + * Note: this translation from ethtool tx/rx notation to the advertisement + * is actually very problematical. Here are some examples: + * + * For tx=0 rx=1, meaning transmit is unsupported, receive is supported: + * + * Local device Link partner + * Pause AsymDir Pause AsymDir Result + * 1 1 1 0 TX + RX - but we have no TX support. + * 1 1 0 1 Only this gives RX only + * + * For tx=1 rx=1, meaning we have the capability to transmit and receive + * pause frames: + * + * Local device Link partner + * Pause AsymDir Pause AsymDir Result + * 1 0 0 1 Disabled - but since we do support tx and rx, + * this should resolve to RX only. + * + * Hence, asking for: + * rx=1 tx=0 gives Pause+AsymDir advertisement, but we may end up + * resolving to tx+rx pause or only rx pause depending on + * the partners advertisement. + * rx=0 tx=1 gives AsymDir only, which will only give tx pause if + * the partners advertisement allows it. + * rx=1 tx=1 gives Pause only, which will only allow tx+rx pause + * if the other end also advertises Pause. + */ +void linkmode_set_pause(unsigned long *advertisement, bool tx, bool rx) +{ + linkmode_mod_bit(ETHTOOL_LINK_MODE_Pause_BIT, advertisement, rx); + linkmode_mod_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, advertisement, + rx ^ tx); +} +EXPORT_SYMBOL_GPL(linkmode_set_pause); -- cgit v1.3.1