This is a note to let you know that I've just added the patch titled
KVM/x86: Export RFDS_NO and RFDS_CLEAR to guests
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-export-rfds_no-and-rfds_clear-to-guests.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a1aa5b868e197f8c2afd9d7eb15dfd134040ab32 Mon Sep 17 00:00:00 2001
From: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
Date: Mon, 11 Mar 2024 12:29:43 -0700
Subject: KVM/x86: Export RFDS_NO and RFDS_CLEAR to guests
From: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
commit 2a0180129d726a4b953232175857d442651b55a0 upstream.
Mitigation for RFDS requires RFDS_CLEAR capability which is enumerated
by MSR_IA32_ARCH_CAPABILITIES bit 27. If the host has it set, export it
to guests so that they can deploy the mitigation.
RFDS_NO indicates that the system is not vulnerable to RFDS, export it
to guests so that they don't deploy the mitigation unnecessarily. When
the host is not affected by X86_BUG_RFDS, but has RFDS_NO=0, synthesize
RFDS_NO to the guest.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1613,7 +1613,8 @@ static unsigned int num_msr_based_featur
ARCH_CAP_SKIP_VMENTRY_L1DFLUSH | ARCH_CAP_SSB_NO | ARCH_CAP_MDS_NO | \
ARCH_CAP_PSCHANGE_MC_NO | ARCH_CAP_TSX_CTRL_MSR | ARCH_CAP_TAA_NO | \
ARCH_CAP_SBDR_SSDP_NO | ARCH_CAP_FBSDP_NO | ARCH_CAP_PSDP_NO | \
- ARCH_CAP_FB_CLEAR | ARCH_CAP_RRSBA | ARCH_CAP_PBRSB_NO | ARCH_CAP_GDS_NO)
+ ARCH_CAP_FB_CLEAR | ARCH_CAP_RRSBA | ARCH_CAP_PBRSB_NO | ARCH_CAP_GDS_NO | \
+ ARCH_CAP_RFDS_NO | ARCH_CAP_RFDS_CLEAR)
static u64 kvm_get_arch_capabilities(void)
{
@@ -1650,6 +1651,8 @@ static u64 kvm_get_arch_capabilities(voi
data |= ARCH_CAP_SSB_NO;
if (!boot_cpu_has_bug(X86_BUG_MDS))
data |= ARCH_CAP_MDS_NO;
+ if (!boot_cpu_has_bug(X86_BUG_RFDS))
+ data |= ARCH_CAP_RFDS_NO;
if (!boot_cpu_has(X86_FEATURE_RTM)) {
/*
Patches currently in stable-queue which might be from pawan.kumar.gupta@xxxxxxxxxxxxxxx are
queue-6.1/documentation-hw-vuln-add-documentation-for-rfds.patch
queue-6.1/x86-rfds-mitigate-register-file-data-sampling-rfds.patch
queue-6.1/x86-mmio-disable-kvm-mitigation-when-x86_feature_clear_cpu_buf-is-set.patch
queue-6.1/kvm-x86-export-rfds_no-and-rfds_clear-to-guests.patch
