linux-kernel - [PATCH] arch/powerpc/kvm: Avoid extra checks when emulating HFSCR bits

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Date: Wed, 26 Jun 2024 18:04:45 +0530
From: Gautam Menghani <gautam@...ux.ibm.com>
To: mpe@...erman.id.au, npiggin@...il.com, christophe.leroy@...roup.eu,
        naveen.n.rao@...ux.ibm.com
Cc: Gautam Menghani <gautam@...ux.ibm.com>, linuxppc-dev@...ts.ozlabs.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] arch/powerpc/kvm: Avoid extra checks when emulating HFSCR bits

When a KVM guest tries to use a feature disabled by HFSCR, it exits to
the host for emulation support, and the code checks for all bits which
are emulated. Avoid checking all the bits by using a switch case.

Signed-off-by: Gautam Menghani <gautam@...ux.ibm.com>
---
 arch/powerpc/kvm/book3s_hv.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 99c7ce825..a72fd2543 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1922,14 +1922,22 @@ static int kvmppc_handle_exit_hv(struct kvm_vcpu *vcpu,
 
 		r = EMULATE_FAIL;
 		if (cpu_has_feature(CPU_FTR_ARCH_300)) {
-			if (cause == FSCR_MSGP_LG)
+			switch (cause) {
+			case FSCR_MSGP_LG:
 				r = kvmppc_emulate_doorbell_instr(vcpu);
-			if (cause == FSCR_PM_LG)
+				break;
+			case FSCR_PM_LG:
 				r = kvmppc_pmu_unavailable(vcpu);
-			if (cause == FSCR_EBB_LG)
+				break;
+			case FSCR_EBB_LG:
 				r = kvmppc_ebb_unavailable(vcpu);
-			if (cause == FSCR_TM_LG)
+				break;
+			case FSCR_TM_LG:
 				r = kvmppc_tm_unavailable(vcpu);
+				break;
+			default:
+				break;
+			}
 		}
 		if (r == EMULATE_FAIL) {
 			kvmppc_core_queue_program(vcpu, SRR1_PROGILL |
-- 
2.45.2