Mailing List Archive

[xen stable-4.16] x86: Expose more MSR_ARCH_CAPS to hwdom
commit 2a362668cb4ad9a0784c4592968f881d7746ec0f
Author: Jason Andryuk <jandryuk@gmail.com>
AuthorDate: Mon Aug 15 15:32:31 2022 +0200
Commit: Jan Beulich <jbeulich@suse.com>
CommitDate: Mon Aug 15 15:32:31 2022 +0200

x86: Expose more MSR_ARCH_CAPS to hwdom

commit e46474278a0e ("x86/intel: Expose MSR_ARCH_CAPS to dom0") started
exposing MSR_ARCH_CAPS to dom0. More bits in MSR_ARCH_CAPS have since
been defined, but they haven't been exposed. Update the list to allow
them through.

As one example, this allows a Linux Dom0 to know that it has the
appropriate microcode via FB_CLEAR. Notably, and with the updated
microcode, this changes dom0's
/sys/devices/system/cpu/vulnerabilities/mmio_stale_data changes from:

"Vulnerable: Clear CPU buffers attempted, no microcode; SMT Host state unknown"

to:

"Mitigation: Clear CPU buffers; SMT Host state unknown"

This exposes the MMIO Stale Data and Intel Branch History Injection
(BHI) controls as well as the page size change MCE issue bit.

Fixes: commit 2ebe8fe9b7e0 ("x86/spec-ctrl: Enumeration for MMIO Stale Data controls")
Fixes: commit cea9ae062295 ("x86/spec-ctrl: Enumeration for new Intel BHI controls")
Fixes: commit 59e89cdabc71 ("x86/vtx: Disable executable EPT superpages to work around CVE-2018-12207")
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: e83cd54611fec5b7a539fa1281a14319143490e6
master date: 2022-08-09 16:35:25 +0100
---
xen/arch/x86/msr.c | 9 +++++++--
xen/include/asm-x86/msr-index.h | 2 ++
2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
index da305c7aa4..103703dfc0 100644
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -71,7 +71,9 @@ static void __init calculate_host_policy(void)
mp->arch_caps.raw &=
(ARCH_CAPS_RDCL_NO | ARCH_CAPS_IBRS_ALL | ARCH_CAPS_RSBA |
ARCH_CAPS_SKIP_L1DFL | ARCH_CAPS_SSB_NO | ARCH_CAPS_MDS_NO |
- ARCH_CAPS_IF_PSCHANGE_MC_NO | ARCH_CAPS_TSX_CTRL | ARCH_CAPS_TAA_NO);
+ ARCH_CAPS_IF_PSCHANGE_MC_NO | ARCH_CAPS_TSX_CTRL | ARCH_CAPS_TAA_NO |
+ ARCH_CAPS_SBDR_SSDP_NO | ARCH_CAPS_FBSDP_NO | ARCH_CAPS_PSDP_NO |
+ ARCH_CAPS_FB_CLEAR | ARCH_CAPS_RRSBA | ARCH_CAPS_BHI_NO);
}

static void __init calculate_pv_max_policy(void)
@@ -160,7 +162,10 @@ int init_domain_msr_policy(struct domain *d)

mp->arch_caps.raw = val &
(ARCH_CAPS_RDCL_NO | ARCH_CAPS_IBRS_ALL | ARCH_CAPS_RSBA |
- ARCH_CAPS_SSB_NO | ARCH_CAPS_MDS_NO | ARCH_CAPS_TAA_NO);
+ ARCH_CAPS_SSB_NO | ARCH_CAPS_MDS_NO | ARCH_CAPS_IF_PSCHANGE_MC_NO |
+ ARCH_CAPS_TAA_NO | ARCH_CAPS_SBDR_SSDP_NO | ARCH_CAPS_FBSDP_NO |
+ ARCH_CAPS_PSDP_NO | ARCH_CAPS_FB_CLEAR | ARCH_CAPS_RRSBA |
+ ARCH_CAPS_BHI_NO);
}

d->arch.msr = mp;
diff --git a/xen/include/asm-x86/msr-index.h b/xen/include/asm-x86/msr-index.h
index 3cb942eeac..c601d88993 100644
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -71,6 +71,8 @@
#define ARCH_CAPS_PSDP_NO (_AC(1, ULL) << 15)
#define ARCH_CAPS_FB_CLEAR (_AC(1, ULL) << 17)
#define ARCH_CAPS_FB_CLEAR_CTRL (_AC(1, ULL) << 18)
+#define ARCH_CAPS_RRSBA (_AC(1, ULL) << 19)
+#define ARCH_CAPS_BHI_NO (_AC(1, ULL) << 20)

#define MSR_FLUSH_CMD 0x0000010b
#define FLUSH_CMD_L1D (_AC(1, ULL) << 0)
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.16